Maharashtra HSC IT Science key terms

Data is a raw collection of unprocessed facts, figures, or symbols. Information is data that has been organised, processed, and given context so it becomes meaningful and useful for decision-making.

The sequence of steps a computer follows to turn raw input into useful output: input, processing, storage, and output. Control and feedback link these stages into a working system.

The main chip that fetches, decodes, and executes program instructions. It contains the arithmetic logic unit for calculations and comparisons, plus control and register units that coordinate the rest of the hardware.

Fast internal storage the CPU accesses directly, namely RAM and ROM. RAM is volatile and holds running programs and data; ROM is non-volatile and holds start-up firmware such as the BIOS.

Non-volatile media that keeps data permanently when power is off, such as hard disks, SSDs, pen drives, and optical discs. It is slower and cheaper per byte than primary memory.

The set of programs and related data that instructs hardware what to do. System software manages the machine, while application software performs user tasks such as word processing or browsing.

A compiler translates an entire source program into machine code before execution and reports all errors together. An interpreter translates and runs one statement at a time, stopping at the first error.

The process of rewriting a value from one base to another, for example binary to decimal or decimal to hexadecimal. Place-value weights of each digit are used, and binary groups of four map to one hex digit.

A bit is one binary digit, either 0 or 1, the smallest unit of data. A byte is a group of eight bits and typically stores one character; larger units are kilobyte, megabyte, and gigabyte.

System software that acts as an interface between the user and hardware. It manages processes, memory, files, and devices, and provides services on which application programs depend.

The core part of an operating system that stays in memory and directly controls hardware. It handles scheduling, memory, and device interrupts, while user programs request its services through system calls.

A controlled request made by a program to the operating system kernel for a privileged service such as reading a file, creating a process, or sending output to a device.

A process is a program in execution with its own memory space. A thread is a smaller unit of execution inside a process that shares that memory, so threads communicate faster but must be synchronised.

A technique where the operating system uses part of secondary storage as an extension of RAM, letting programs run even when physical memory is short. It relies on paging and swapping.

The method an operating system uses to name, store, organise, and retrieve files on a disk. It defines directory structure, permissions, and allocation, for example FAT32, NTFS, and ext4.

An absolute path states the full location from the root, such as /home/user/notes.txt. A relative path is interpreted from the current working directory, such as notes.txt or ../images/logo.png.

A tag is the markup written in angle brackets, such as

, that marks up content. An element is the complete unit of opening tag, content, and closing tag, which the browser renders.

A name-value pair written inside an opening tag that supplies extra information about an element, such as src, href, id, or alt. Attributes never appear as visible page text.

A pattern that chooses which HTML elements a CSS rule applies to. Common forms are the type selector p, the class selector .note, the id selector #header, and descendant combinations.

The rule that decides which conflicting style declaration wins. Inline styles beat ids, ids beat classes and attributes, and those beat type selectors; equal specificity is resolved by source order.

The layout model in which every element is a box made of content, padding, border, and margin. Padding sits inside the border, margin outside it, and box-sizing changes how width is calculated.

An approach that makes a page display well on phones, tablets, and desktops. It uses fluid grids, flexible images, and media queries that apply different CSS rules at different viewport widths.

The viewport is the visible area of a browser window. A media query is a CSS conditional block that applies styles only when conditions such as minimum width or orientation are met.

The tree of objects a browser builds from an HTML page, where every element, attribute, and text node is reachable and editable. JavaScript uses it to read and change page content dynamically.

An action or occurrence a web page can detect and respond to, such as a click, keypress, load, or form submit. Handlers attached with addEventListener run code when the event fires.

Client-side code runs in the visitor's browser, giving fast feedback but remaining visible and bypassable. Server-side code runs on the web server, so it can safely access databases and protect logic.

Checking that user input meets required rules before it is accepted. Client-side validation gives quick feedback in the browser, while server-side validation is the reliable check performed again on the server.

A built-in array available in every scope, such as $_GET, $_POST, $_SESSION, and $_SERVER. These carry request data, session state, and server details into PHP scripts.

GET sends form data appended to the URL, so it is visible, bookmarkable, and length-limited. POST sends data in the request body, so it suits sensitive or large submissions and is not shown in the address bar.

A cookie is a small file stored in the browser and sent back with each request. A session stores data on the server and identifies the user by a session ID, usually kept in a cookie.

An attack in which crafted input is inserted into a database query so the attacker can read or alter data. It is prevented by prepared statements with bound parameters and by validating input.

A query template sent to the database with placeholders, then filled with values separately. The database treats those values as data, never as SQL code, which blocks injection.

A column, or set of columns, whose value uniquely identifies each row of a table. It must be unique and cannot be null; a table can have only one primary key.

A column in one table that refers to the primary key of another table, enforcing referential integrity. It prevents orphan rows and expresses relationships between tables.

The process of structuring tables to reduce redundancy and avoid update, insert, and delete anomalies. First, second, and third normal forms remove repeating groups and partial and transitive dependencies.

Data definition language statements such as CREATE, ALTER, and DROP change the structure of database objects. Data manipulation language statements such as SELECT, INSERT, UPDATE, and DELETE work on the rows.

Any unlawful act in which a computer, network, or digital device is the target, the tool, or the storage medium. Examples include hacking, identity theft, phishing, and data theft.

India's main legislation on electronic commerce and cyber offences. It gives legal recognition to electronic records and digital signatures and defines penalties for offences such as unauthorised access and data tampering.

A social-engineering attack that tricks a user into revealing credentials or personal data, often through fake emails or lookalike login pages. Verifying the sender and URL helps prevent it.

An encrypted value created with a sender's private key that proves the authenticity and integrity of a message. The receiver verifies it with the sender's public key.

A network of physical devices fitted with sensors and network connections that collect and exchange data, such as smart meters and fitness bands. It depends on low-power communication and cloud back ends.

Delivering computing resources such as servers, storage, and software over the internet on demand. Service models are IaaS, PaaS, and SaaS; deployment models include public, private, and hybrid.

The fifth generation of mobile networks, offering very high data rates, low latency, and many simultaneous connections. These features support IoT, connected vehicles, and real-time applications.

The branch of computing that builds systems able to perform tasks associated with human intelligence, such as learning, reasoning, and pattern recognition. Machine learning and natural language processing are subfields.