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HKDSE ICT practice questions

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Question 1Information processing

A school library system stores each borrower's record with a unique borrower ID. Which of the following best describes the role of the borrower ID in the database?

  1. It is the primary key that uniquely identifies each record in the table Correct answer.
  2. It is an index that sorts the records alphabetically
  3. It is a foreign key linking the table to the book catalogue
  4. It is a field that stores the total number of books borrowed

Explanation

A primary key is a field (or combination of fields) whose value is unique for every record in a table, so it can identify each row unambiguously. The borrower ID is chosen for that purpose because no two borrowers share the same ID. Foreign keys, indexes and calculated totals serve different purposes.

Question 2Information processing

In a data processing system, which sequence correctly represents the order of the data processing cycle?

  1. Input, processing, output, storage Correct answer.
  2. Storage, output, input, processing
  3. Output, storage, processing, input
  4. Processing, input, storage, output

Explanation

The data processing cycle begins when data is captured as input, is then manipulated during processing, produces information as output, and may be retained in storage for later use. The other sequences place a later stage before an earlier one, which breaks the logical flow of the cycle.

Question 3Information processing

A hospital wants each patient record to hold exactly one date of birth and no more than one. Which property should be applied to the date-of-birth field?

  1. Set the field as a repeating group
  2. Set the field as a single-valued attribute Correct answer.
  3. Set the field as a multi-valued attribute
  4. Set the field as a foreign key

Explanation

A single-valued attribute holds at most one value for each entity instance, which matches a person having one date of birth. Multi-valued attributes and repeating groups allow several values per record, which would permit duplicate or conflicting birth dates. A foreign key is about relationships, not cardinality of a value.

Question 4Information processing

Which of the following is an example of data rather than information?

  1. A summary stating that the average temperature rose by two degrees
  2. A recommendation to replace the cooling unit
  3. A conclusion that the air conditioning failed
  4. A list of raw temperature readings taken every hour Correct answer.

Explanation

Data consists of raw, unprocessed facts and figures, such as individual temperature readings before any interpretation. Information is data that has been processed into a meaningful form, such as an average, a conclusion or a recommendation. The other options are all outcomes of processing.

Question 5Information processing

A company scans paper invoices and converts the printed text into editable digital text. Which technology performs this conversion?

  1. Barcode scanning
  2. Optical character recognition Correct answer.
  3. Radio frequency identification
  4. Magnetic ink character recognition

Explanation

Optical character recognition analyses an image of printed or handwritten text and converts the shapes into machine-readable characters. Barcode and RFID systems read identifiers rather than full text. Magnetic ink recognition reads specially printed characters using magnetic properties, not general printed text.

Question 6Information processing

Which of the following is a valid reason for using a validation check rather than a verification method when data is entered?

  1. Validation detects transmission errors using check digits
  2. Validation confirms that two operators typed the same value
  3. Validation compares the entered data with the original document twice
  4. Validation checks whether data falls within acceptable rules, while verification confirms that the data matches the source Correct answer.

Explanation

Validation tests whether input satisfies predefined rules such as a range or a format, so it detects data that is unreasonable even if it was typed exactly as written. Verification instead checks that what was entered matches the source document or the original entry. The two concepts address different kinds of error.

Question 7Information processing

A file stores records of equal length, and each record can be located directly by calculating its offset from the start of the file. Which file organization is being described?

  1. Indexed sequential file organization
  2. Direct (random) file organization Correct answer.
  3. Sequential file organization
  4. Serial file organization

Explanation

In direct or random file organization, a record's address is computed from its key, so the record can be reached without reading preceding records. This requires fixed-length records and a suitable hashing or addressing scheme. Sequential and serial files must be read in order, and indexed sequential files use an index.

Question 8Information processing

Which of the following correctly distinguishes a bit from a byte?

  1. A bit stores one character, and a byte stores one instruction
  2. A bit is a group of eight bytes, and a byte is a single binary digit
  3. A bit is a binary digit, and a byte is a group of eight bits Correct answer.
  4. A bit is a decimal digit, and a byte is a hexadecimal digit

Explanation

A bit is the smallest unit of data and holds a single binary value, 0 or 1. A byte is conventionally a group of eight bits and is commonly used to store one character in ASCII. The other statements reverse or misstate these definitions.

Question 9Information processing

A student types a class list into a spreadsheet and then sorts the rows by surname. Which stage of the data processing cycle does the sorting represent?

  1. Processing Correct answer.
  2. Collection
  3. Output
  4. Input

Explanation

Sorting rearranges captured data into a more useful order, which is a manipulation performed on data already entered, so it belongs to processing. Input is the capture of the data, and output is the presentation of results. Collection is part of the input stage rather than a separate manipulation.

Question 10Information processing

A form field for a Hong Kong identity card number must accept exactly one letter followed by six digits in brackets. Which validation check is most appropriate?

  1. A consistency check between two fields
  2. A presence check that the field is not empty
  3. A range check on the numeric value
  4. A format check on the pattern of the characters Correct answer.

Explanation

A format check verifies that the characters entered follow a required pattern, such as a letter followed by digits and a check character. Range checks compare numeric values against limits, presence checks only test for emptiness, and consistency checks compare related fields. Only the format check enforces the character pattern.

Question 11Information processing

An online shop stores orders in one table and customers in another, with each order holding a customer ID. What is the main purpose of this arrangement?

  1. To allow customers to be deleted without affecting orders
  2. To reduce redundant storage of customer details and avoid update anomalies Correct answer.
  3. To make each order record longer by adding extra fields
  4. To ensure that orders can be sorted by customer name

Explanation

Splitting data into related tables so that customer details appear once is normalization, which removes redundancy and the insertion, update and deletion anomalies that duplicated data causes. The customer ID in the order table acts as a foreign key to link the tables. Sorting and record length are not the objectives.

Question 12Information processing

A payroll program calculates an employee's pay as hours worked multiplied by the hourly rate. If the stored hourly rate is 0, what type of error is this most likely to produce?

  1. A processing error caused by invalid input data Correct answer.
  2. A transcription error made by the operator
  3. A transmission error during data transfer
  4. A syntax error in the program code

Explanation

The formula itself is correct, but a zero hourly rate is unreasonable input, so the resulting pay is wrong. This is a processing error arising from invalid data that should have been blocked by a validation check such as a range check. Syntax, transcription and transmission errors have different causes.

Question 13Information processing

Which statement best explains why a check digit can detect a single mistyped digit in an account number?

  1. The check digit is always the largest digit in the number
  2. The check digit is a copy of the first digit for comparison
  3. The check digit records the total number of digits in the number
  4. The check digit is recalculated from the other digits, so a change in any digit usually alters the expected check digit Correct answer.

Explanation

A check digit is derived from the other digits by a fixed rule, such as a weighted sum modulo a number. When a digit is mistyped, the recomputed check digit usually no longer matches the stored one, so the error is flagged. It is not a count, a maximum or a duplicate of another digit.

Question 14Information processing

A supermarket wants to speed up checkout and automatically update stock levels when items are sold. Which data capture method is most suitable at the point of sale?

  1. Using a magnetic stripe card reader for each product
  2. Recording sales on paper and keying them in later
  3. Asking the cashier to type each product name
  4. Scanning the barcode on each product Correct answer.

Explanation

A barcode encodes the product identifier, so scanning captures the data quickly and accurately and lets the system look up the price and deduct stock immediately. Manual typing is slower and error-prone, card readers identify payment cards rather than products, and later keying delays stock updates.

Question 15Information processing

A school stores student records in a file. Which change would most reduce data redundancy compared with storing each student's class teacher's name and phone number in every student record?

  1. Store the teacher's details in a text note attached to each student record
  2. Store the teacher's name twice in each student record for safety
  3. Store a teacher ID in the student record and keep teacher details in a separate teacher table Correct answer.
  4. Store the teacher's phone number only in the first student record of each class

Explanation

Keeping teacher details in one table and referencing them by a teacher ID means each fact is stored once, which removes redundancy and the anomalies that repeated data causes. Duplicating data, storing it once per class arbitrarily, or embedding it in free text all retain or worsen the redundancy problem.

Question 16Information processing

A web form requires a user to enter an email address twice and compares the two entries before submission. What is this technique called?

  1. Check digit verification
  2. Format validation
  3. Double entry verification Correct answer.
  4. Range validation

Explanation

Double entry verification asks for the same data twice, often by two people or two entries, and compares the results so that a typing slip is detected. It confirms that the data matches what was intended rather than testing whether it obeys a rule. Range, check digit and format checks test rules instead.

Question 17Information processing

A company converts all customer records to a new database system. During transfer, some characters are corrupted because of an encoding mismatch. What type of error is this?

  1. A processing error
  2. A transcription error
  3. A transmission error Correct answer.
  4. A logical error in the formula

Explanation

Data corrupted while being moved from one system to another is a transmission error, often caused by incompatible character encodings or faulty links. Transcription errors arise from mistyping, processing errors from incorrect manipulation, and formula errors from faulty logic. The corruption happens during transfer, not during calculation.

Question 18Information processing

Which of the following best explains why indexed sequential file organization suits a system that needs both batch reports in key order and occasional direct lookups?

  1. Records are stored on tape, which supports both reading modes equally well
  2. An index allows direct access to a record while records remain stored in key order for sequential reading Correct answer.
  3. Each record is hashed to a computed address so that no index is needed
  4. Records are stored in arrival order so that new records are always appended at the end

Explanation

Indexed sequential organization keeps records physically ordered by key, which supports efficient sequential processing for batch reports, and maintains an index that allows individual records to be located directly. Hashing gives direct access but not ordered sequential reading, and arrival-order or tape storage does not provide the index.

Question 19Information processing

A file contains records of varying length, and each record begins with a field giving its length. How can the next record be located?

  1. Read the file backwards from the end
  2. Search the whole file from the beginning for a delimiter
  3. Multiply the record number by a fixed record size
  4. Read the length field and skip forward by that number of bytes Correct answer.

Explanation

When records vary in length, a length prefix tells the system exactly how many bytes the current record occupies, so the start of the next record is found by adding that length to the current position. A fixed record size would not apply, and scanning or reading backwards would be inefficient and unnecessary.

Question 20Information processing

A student claims that a database field storing a telephone number should be defined as a numeric data type. Which response is most appropriate?

  1. A numeric type is better because arithmetic will be performed on telephone numbers
  2. A text type is better because telephone numbers are identifiers that may contain leading zeros or symbols and are not used in arithmetic Correct answer.
  3. A Boolean type is better because a telephone number is either present or absent
  4. A date type is better because telephone numbers change over time

Explanation

Data types should reflect how a value is used. Telephone numbers are identifiers: leading zeros must be preserved and symbols such as plus signs or spaces may appear, and no arithmetic is performed on them, so a text type is appropriate. Numeric, Boolean and date types do not fit these requirements.

Question 21Information processing

A company processes one million sales records each night to produce daily totals. Which processing mode is being used?

  1. Batch processing Correct answer.
  2. Time-sharing processing
  3. Interactive processing
  4. Real-time processing

Explanation

Batch processing collects transactions over a period and processes them together at a scheduled time, which suits producing daily totals from large volumes of records. Real-time processing handles each transaction immediately, and interactive and time-sharing modes involve users working with the system as it runs.

Question 22Information processing

A bank must update account balances the moment a customer withdraws cash at an ATM. Which processing mode is required, and why?

  1. Batch processing, because transactions can be grouped and processed at midnight
  2. Serial processing, because records must be read in the order they were stored
  3. Real-time processing, because each transaction must be processed immediately to keep the balance accurate Correct answer.
  4. Offline processing, because the ATM does not need to contact the bank

Explanation

Real-time processing handles each transaction as it happens so that the balance reflects the withdrawal immediately and further withdrawals cannot overdraw the account. Batch processing would leave the balance stale until the run, and serial or offline processing cannot guarantee an up-to-date balance at the point of withdrawal.

Question 23Information processing

A designer must choose a data capture method for a stocktake in which hundreds of items on shelves are counted quickly. Which combination of method and justification is strongest?

  1. RFID tags read by a handheld reader, because many tags can be read without direct line of sight and without individual scanning Correct answer.
  2. Manual entry of each item code, because it requires no special hardware
  3. Magnetic ink character recognition, because it reads printed labels at a distance
  4. Optical mark recognition, because it detects marks on shelf labels

Explanation

RFID readers can interrogate many tags in range without line of sight, which greatly speeds up counting large numbers of items. Manual entry is slow and error-prone, magnetic ink recognition requires special printed characters read at close range, and optical mark recognition reads pencil marks on forms rather than identifying products.

Question 24Information processing

A system stores each student's date of birth and also stores the student's age, which is recalculated only when a record is edited. What problem does this design create?

  1. The design removes all redundancy, which makes the database unusable
  2. Storing the date of birth violates the rule that each record needs a primary key
  3. The age field should be a foreign key referencing the date field
  4. Storing derived data causes inconsistency because the stored age becomes out of date Correct answer.

Explanation

Age can be derived from the date of birth and the current date, so storing it duplicates information that changes over time. Unless it is recalculated continuously, the stored age will disagree with the derived value, which is a data inconsistency. Redundancy should be removed, not added, and derived data is best computed when needed.

Question 25Information processing

A validation rule requires an examination mark to be an integer from 0 to 100. A student enters 85.5. Which statement about the outcome is most accurate?

  1. A check digit will detect that 85.5 is not an integer
  2. The range check will always reject 85.5 because it is not a whole number
  3. The presence check will reject 85.5 because the field is not empty
  4. A range check alone may accept 85.5, so a separate data type or format check is needed to reject non-integers Correct answer.

Explanation

A range check tests only whether a value lies between the limits, and 85.5 lies within 0 to 100, so it can pass. Rejecting a non-integer requires an additional check on the data type or format, such as testing for whole numbers. Presence and check digit checks do not test integrality.

Question 26Information processing

A library system stores the borrowing history of every book ever lent, including the borrower name, class and date. Which term best describes this collection of related files and the programs that manage it?

  1. A spreadsheet
  2. A word-processing document
  3. A bitmap image
  4. A database Correct answer.

Explanation

A database is an organised collection of related data stored so that it can be accessed, managed and updated, together with the software that controls it. The borrowing records form related files with a defined structure, which is exactly what a database provides.

Question 27Information processing

In a school's student file, each record contains the student name, class, date of birth and a unique student number. What is the student number called in this context?

  1. A foreign key
  2. A key field Correct answer.
  3. A check digit
  4. A data type

Explanation

A field that uniquely identifies each record in a file is a key field (primary key). The student number is unique for each student, so it can be used to locate a specific record without ambiguity.

Question 28Information processing

A teacher wants to record whether each student has submitted a project, using only the values Yes or No. Which data type is most appropriate for this field?

  1. Character string
  2. Real
  3. Boolean Correct answer.
  4. Date

Explanation

A Boolean field stores one of two logical values, such as true/false or Yes/No, so it matches the two-state nature of submission. Using it prevents other values from being entered into the field.

Question 29Information processing

A hospital file stores each patient's identity card number, name and address. The data entry clerk must ensure that the identity card number entered matches the format of the identity document. Which type of validation is being applied?

  1. Consistency check
  2. Format check Correct answer.
  3. Existence check
  4. Range check

Explanation

A format check verifies that data follows a required pattern, such as a letter followed by digits and a check character. The identity card number must fit a fixed structure, so a format check is the matching validation.

Question 30Information processing

A warehouse stores 500,000 product records on magnetic disk. Most records are updated during the day, and individual records are frequently retrieved by product code. Which file organisation is most suitable?

  1. Serial organisation
  2. Sequential organisation
  3. Indexed sequential organisation used only for batch runs
  4. Random (direct) organisation Correct answer.

Explanation

Random organisation uses a hashing or direct-address method so any record can be reached in roughly the same short time, which suits frequent individual retrieval and updating. Sequential and serial files require scanning many records before the target is reached.

Question 31Information processing

A travel agency system stores a booking record that contains the customer name, tour code and departure date. The same customer books three tours and the name is typed three times. What is the main problem caused by this design?

  1. The tour code cannot be a key field
  2. Data redundancy leading to possible inconsistency Correct answer.
  3. Insufficient validation on the departure date
  4. Too few fields for the tour code

Explanation

Repeating the customer name in every booking stores the same fact many times, which is data redundancy. If one copy is later corrected and others are not, the file becomes inconsistent, so redundancy threatens data integrity.

Question 32Information processing

A system records a student's class and also stores a separate field for the number of students in that class, updated only when the class list is edited. A teacher later moves a student between classes. Which data problem is most likely?

  1. The class-size field becomes inconsistent with the actual class list Correct answer.
  2. The record length changes from fixed to variable
  3. The student's name violates a range check
  4. The class field becomes a foreign key automatically

Explanation

Storing a derived value such as class size separately means it must be recalculated whenever the underlying list changes. If the move is not followed by a recalculation, the stored size contradicts the real count, which is a data inconsistency.

Question 33Information processing

A school wants a report listing every student whose average mark is below 40, sorted by class. Which database operation produces the list of students?

  1. Append new student records to the file
  2. Query the student file with a selection condition on average mark Correct answer.
  3. Update the average mark field for all students
  4. Delete records with an average mark below 40

Explanation

A query applies selection criteria to retrieve only the records that match, here those with an average mark below 40. The result can then be sorted by class for reporting, without altering the stored data.

Question 34Information processing

A payroll file is stored in ascending order of employee number. A clerk needs to find one employee's record. Explain why a sequential search on this file may be slow, and which property of the file could be exploited to speed up the search.

  1. The file is ordered, so a linear search must read every record before stopping
  2. The file stores variable-length records, so direct addressing is required
  3. The file is ordered, so a binary search can halve the search range repeatedly Correct answer.
  4. The file is unordered, so hashing is impossible

Explanation

A sequential search may examine records one by one until the target is found, which is slow for a large file. Because the records are already in ascending order of the key, a binary search can compare the middle record and discard half the remaining records each time, reducing the number of comparisons sharply.

Question 35Computer system fundamentals

In the stored-program concept, what is kept in main memory during execution?

  1. Both program instructions and the data being processed Correct answer.
  2. Only the instructions, since data is held in registers
  3. Neither, because everything is streamed from secondary storage
  4. Only the data, since instructions stay in the control unit

Explanation

The stored-program (von Neumann) concept places both the program's instructions and its data in the same main memory, addressed by location. The CPU fetches instructions from memory and reads or writes data there in the same way, which is what makes general-purpose computing possible.

Question 36Computer system fundamentals

Which statement correctly describes the difference between RAM and ROM?

  1. RAM is non-volatile and read-only; ROM is volatile and writable
  2. RAM is volatile and normally writable; ROM is non-volatile and normally read-only Correct answer.
  3. Both RAM and ROM lose their contents when power is removed
  4. RAM holds only the operating system while ROM holds all user files

Explanation

RAM loses its contents when power is removed (volatile) and can be written during normal operation, whereas ROM retains its contents without power and is normally only read. Firmware such as the bootstrap loader is typically held in ROM.

Question 37Computer system fundamentals

A student wants a portable medium to submit a 4 GB video project. Which storage medium is most suitable?

  1. A Blu-ray disc
  2. A CD-R disc
  3. A 16 GB USB flash drive Correct answer.
  4. A 1.44 MB floppy disk

Explanation

A 16 GB USB flash drive has enough capacity for the 4 GB file and is small, rewritable and widely supported, making it suitable for submission. The other media either have far too little capacity or are awkward to rewrite.

Question 38Computer system fundamentals

Which of the following is an example of system software?

  1. A photo editor
  2. A web browser
  3. A spreadsheet application
  4. An operating system Correct answer.

Explanation

System software manages the hardware and provides a platform for other programs; the operating system is the principal example. Spreadsheets, browsers and photo editors are application software written to perform user tasks.

Question 39Computer system fundamentals

Which device is classified as an input device?

  1. A plotter
  2. A barcode reader Correct answer.
  3. A monitor
  4. A laser printer

Explanation

A barcode reader captures data from the outside world and sends it into the computer, so it is an input device. Plotters, printers and monitors all present processed results to the user and are output devices.

Question 40Computer system fundamentals

What is the main purpose of cache memory in a computer system?

  1. To reduce the average time the CPU waits for data from main memory Correct answer.
  2. To back up user files automatically
  3. To store the operating system permanently
  4. To convert analogue signals into digital data

Explanation

Cache is small, fast memory close to the CPU that holds recently or frequently used instructions and data. Because the CPU can read it much faster than main memory, it lowers the average memory access time and keeps the processor busy.

Question 41Computer system fundamentals

Which of the following is an example of an operating system function rather than an application feature?

  1. Correcting spelling in a document
  2. Allocating memory to running processes Correct answer.
  3. Designing a poster layout
  4. Editing the colours in an image

Explanation

Memory allocation among running processes is a core operating system responsibility, along with process scheduling, file management and device management. The other options are tasks performed by application programs.

Question 42Computer system fundamentals

A school network has one server holding all student files, and each classroom PC accesses those files over the LAN. Which term best describes this arrangement?

  1. A peer-to-peer network
  2. A wide area network
  3. A client-server network Correct answer.
  4. A stand-alone computer system

Explanation

A dedicated server provides shared resources such as files to client machines that request them, which is the defining pattern of a client-server network. Because the machines are in one campus linked by a LAN, it is not a WAN, and the presence of a dedicated server rules out peer-to-peer.

Question 43Computer system fundamentals

A 2 KiB file is stored on a disk. How many bits does the file contain?

  1. 2048 bits
  2. 2097152 bits
  3. 16384 bits Correct answer.
  4. 1024 bits

Explanation

1 KiB equals 1024 bytes, so 2 KiB is 2048 bytes. Since each byte is 8 bits, the total is 2048 × 8 = 16384 bits.

Question 44Computer system fundamentals

The denary number 45 is to be stored in an 8-bit register. What is its binary representation?

  1. 00010110
  2. 00101101 Correct answer.
  3. 00110101
  4. 10110100

Explanation

45 = 32 + 8 + 4 + 1, so bits for 32, 8, 4 and 1 are set, giving 00101101. Checking place values from the left confirms the sum equals 45.

Question 45Computer system fundamentals

A signed integer is stored using two's complement in 8 bits. What denary value does 11111111 represent?

  1. 128
  2. -1 Correct answer.
  3. 255
  4. -127

Explanation

In 8-bit two's complement the leading 1 marks a negative number. Inverting all bits gives 00000000, and adding 1 gives 1, so the value is -1. Equivalently, -128 + 127 = -1.

Question 46Computer system fundamentals

Which statement about the fetch-decode-execute cycle is correct?

  1. The program counter holds the instruction just decoded
  2. The instruction is decoded after it is fetched into the instruction register Correct answer.
  3. Execution always writes a result to secondary storage
  4. The accumulator stores the address of the next instruction

Explanation

In the cycle the instruction is first fetched from the address in the program counter into the instruction register, and only then decoded by the control unit. Execution follows decoding, and the program counter, not the accumulator, tracks the next instruction address.

Question 47Computer system fundamentals

Which of the following best describes the role of the control unit in a CPU?

  1. It directs the flow of data and coordinates the other CPU components Correct answer.
  2. It performs arithmetic on integer operands
  3. It converts high-level source code into machine code
  4. It temporarily stores the results of calculations

Explanation

The control unit decodes instructions and issues control signals that coordinate the ALU, registers and memory so each instruction executes correctly. Arithmetic is the ALU's job, and compilation is done by software, not by the CPU's control unit.

Question 48Computer system fundamentals

A file of 6 MB is to be transmitted over a link. Which unit conversion is correct?

  1. 6 MB = 6 000 000 bytes using decimal prefixes Correct answer.
  2. 6 MB = 6 000 bits
  3. 6 MB = 6 291 456 bytes using binary prefixes
  4. 6 MB = 48 000 bytes

Explanation

When SI decimal prefixes are used for storage, 1 MB means 1 000 000 bytes, so 6 MB is 6 000 000 bytes. The value 6 291 456 bytes corresponds to 6 MiB, a binary-prefix quantity, not 6 MB.

Question 49Computer system fundamentals

A bitmap image is 800 × 600 pixels with a colour depth of 24 bits. What is its uncompressed file size in bytes?

  1. 11 520 000 bytes
  2. 1 440 000 bytes Correct answer.
  3. 14 400 bytes
  4. 480 000 bytes

Explanation

The image has 800 × 600 = 480 000 pixels, and at 24 bits each that is 11 520 000 bits. Dividing by 8 bits per byte gives 1 440 000 bytes.

Question 50Computer system fundamentals

Which statement about lossless and lossy compression is correct?

  1. Lossless compression removes data that cannot be recovered
  2. Lossless compression is only possible for text files
  3. Lossy compression permanently discards some data to reduce file size Correct answer.
  4. Lossy compression allows exact reconstruction of the original data

Explanation

Lossy compression reduces size by discarding detail that is judged least noticeable, so the original cannot be rebuilt exactly. Lossless compression instead encodes the data more compactly while allowing perfect reconstruction.