Computer Science Level 3 key terms

A finite, ordered set of unambiguous steps that transforms inputs into a desired output and terminates after a limited number of operations.

A structured, human-readable description of an algorithm using programming-like constructs but no strict syntax, so the logic can be reviewed before coding.

Breaking a large problem into smaller subproblems that can be solved and tested independently, then combined into a complete solution.

Removing detail that is irrelevant to the current purpose so a model or interface exposes only the features needed to solve the problem.

A measure of how an algorithm's running time or memory use grows with input size, usually expressed with big-O notation such as O(n log n).

A technique in which a function calls itself on smaller inputs, requiring a base case to stop and a recursive case to make progress.

A manual record of variable values after each step of an algorithm, used to verify logic, find errors, and demonstrate dry running.

A system of truth values combined with operators such as AND, OR, and NOT, used to build conditions and control program decisions.

A named storage location whose value can change while a program runs; its name, type, and scope determine how it is used.

A classification such as integer, string, or Boolean that defines which values a variable may hold and which operations apply to them.

The region of a program in which a declared name is visible and usable, typically local to a block or function versus global to a module.

A named, reusable block of code that takes parameters, performs a task, and optionally returns a value to the caller.

A named input declared by a function; an argument is the actual value supplied when the function is called.

The result a function sends back to the code that called it, ending execution of that function unless it is void.

Repetition of a block of statements controlled by a loop condition, such as a for loop with a counter or a while loop.

The systematic process of locating, reproducing, and correcting defects in a program using breakpoints, logging, and test cases.

An automated check that exercises one small piece of code in isolation and asserts that its actual output matches the expected output.

Verification that operations receive values of compatible types, performed at compile time in static languages or at run time in dynamic ones.

A fixed-size, indexed collection of elements of the same type stored contiguously, allowing constant-time access by position.

A numeric position identifying an element in an ordered structure; in most languages the first element has index zero.

A linear structure of nodes, each holding data and a reference to the next node, giving cheap insertion but sequential access only.

A last-in, first-out collection supporting push and pop at one end, used for function calls, undo history, and expression evaluation.

A first-in, first-out collection where items are added at the rear and removed from the front, used for scheduling and buffering.

A structure mapping keys to values through a hash function, giving average constant-time lookup, with collisions resolved by chaining or probing.

A tree where each node's left subtree holds smaller keys and its right subtree larger keys, enabling ordered search in logarithmic time when balanced.

A defined order for visiting every node of a tree, such as pre-order, in-order, post-order depth-first, or level-order breadth-first.

Organizing tables to reduce redundancy and update anomalies by separating data according to functional dependencies, typically through third normal form.

A column or combination of columns whose values uniquely identify each row in a table and cannot be null.

A column referencing a primary key in another table, enforcing referential integrity between related records.

A program that translates an entire source file into machine code or intermediate code before execution, reporting syntax errors ahead of time.

A program that reads and executes source code statement by statement, allowing rapid testing but typically slower execution than compiled code.

The binary instruction set a processor executes directly, produced by assembly or compilation and specific to a CPU architecture.

Software that manages hardware, memory, files, and processes, and provides services and scheduling so applications can run safely.

An abstraction giving each process its own address space, with pages mapped to physical memory or disk so programs exceed available RAM.

Small, fast storage between the CPU and main memory that holds recently used data to reduce average access time.

A run-time structure of frames recording active function calls, their local variables, and return addresses; recursion depth is limited by its size.

An agreed set of rules governing message format, ordering, and responses so different systems can communicate reliably.

A numeric label identifying a device on a network, used by routers to forward packets between subnets and across the internet.

Dividing data into packets that travel independently and are reassembled at the destination, sharing network links efficiently.

Transforming readable data into ciphertext with a key so that only authorized parties can recover the original content.

Verifying that a user or system is who it claims to be, using passwords, tokens, certificates, or biometric factors.

Rules deciding which authenticated users may read or change which resources, often expressed as roles and permissions.

A social-engineering attack using deceptive messages that impersonate trusted parties to steal credentials or install malware.

Software written to harm or exploit systems, including viruses, worms, ransomware, and spyware, often spread through downloads or attachments.

Detecting and correcting incomplete, duplicated, or malformed records before analysis so results are accurate and reproducible.

A data point lying far from the rest of the distribution, which may indicate measurement error or a genuine rare event.

A numerical measure of how strongly two variables move together; it does not by itself establish that one causes the other.

Representing data graphically with charts or plots so patterns, trends, and comparisons become easier to perceive and communicate.

Running a model of a system many times with varied inputs to estimate outcomes that are costly or impossible to test directly.

Legal rights over creations such as code, text, and images, covering copyright, patents, and trademarks, and governing reuse.

A license granting permission to use, modify, and redistribute software under stated conditions, such as attribution or share-alike requirements.

Presenting another person's words, code, or ideas as one's own without proper attribution, a breach of academic and professional integrity.

A system recording changes to files over time, enabling history review, branching, and safe collaboration among developers.

Unequal access to devices, connectivity, and digital skills across groups, which affects opportunities in education and employment.

Systematic unfairness in automated decisions arising from biased training data or flawed design, producing unequal outcomes for groups.