AP Computer Science
Principles Vocabulary 2026
| Key Terms, Study Guide,
Practice Questions,
Answers & Exam Review |
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Updated 2026 Questions and Answers
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,Algorithm At its core, an algorithm is really just a generalized, conceptual solution to a
problem that can later be implemented in some real-world form like a computer
program.
Application Program Interface Application program interface (API) is a set of routines, protocols, and tools for
constructing software applications. An API specifies how software components
should interact. In addition, APIs are used when programming graphical user
interface (GUI) components.
Binary A numeric system of base 2 that only uses combinations of the digits zero and one;
this is used in one of the lowest levels of abstraction. Computers operate in binary,
as they store data and perform calculations using only zeros and ones. While a
single binary digit can be used to represent True (1) or False (0) in boolean logic,
multiple binary digits can be used in conjunction to store large numbers and perform
complex functions. Computers translate between binary and what you actually work
with such as numbers and text.
Binary Search A search algorithm that locates the position of a target value within a sorted array by
repeatedly dividing the search interval in half; can only be used when the list is
sorted. Because of its divide-and-conquer approach, the amount of work required to
find an item grows much more slowly with Binary Search than with Sequential
Search. In fact, with this logarithmic behavior
Boolean Function* Any function based on the operations AND, OR, and NOT, and whose elements are
from the domain of Boolean algebra. A function whose arguments, as well as the
function itself, assume values from a two-element set (usually {0,1})
Central Processing Unit CPU, or processor, is the brains of the computer where most calculations take
place. Contains the circuitry necessary to interpret and execute program
instructions.
Computational Artifact Something created by a human using a computer and can be, but is not limited to, a
program, an image, an audio, a video, a presentation, or web page file
Cryptography The science of coding and decoding messages in order to keep them secure.
Coding takes place using a key that ideally is known only by the sender and
intended recipient of the message.
Floating Point Numbers As the name implies, floating point numbers are numbers that contain floating
decimal points. Examples include, the numbers 5.5, 0.001, and -2,345.6789.
Numbers without decimal places are called integers. Computers recognize real
numbers that contain fractions as floating point numbers.
Hexadecimal Hexadecimal describes a base-16 number system. That is, it describes a numbering
system containing 16 sequential numbers as base units (including 0) before adding
a new position for the next number. The hexadecimal numbers are 0-9 and then use
the letters A-F. Used to represent digital data because it utilizes fewer digits than
binary.
Integers An integer is a whole number (not a fraction) that can be positive, negative, or zero.
In computer science, an integer is a datum of integral data type, a data type that
represents some finite subset of the mathematical integers. Integral data types may
be of different sizes and may or may not be allowed to contain negative values.
Iterations Iteration is the repetition of part of an algorithm until a condition is met or for a
specified number of times. This is often called a 'loop'. Recursive functions
repeatedly execute themselves as part of their operation. Upon completing all
instructions and resetting to the first one iteration has been completed.
, Libraries In computer science, a library is a collection of non-volatile resources that a
program can use often to develop software. Libraries are particularly useful for
storing frequently used routines because you do not need to explicitly link them to
every program that uses them. The linker automatically looks in libraries for routines
that it does not find elsewhere. Resources which may be found in libraries include
data, documentation, message templates, pre-written code, classes, or values.
Linear/Sequential Search A process that checks every element in the list sequentially until the desired
element is found or all elements have been searched. Can be used in any type of
list. Has linear performance.
Lossless Data Compression With lossless compression, every single bit of data that was originally in the file
remains after the file is uncompressed. All of the information is completely restored.
This is generally the technique of choice for text or spreadsheet files, where the loss
of words or financial data could pose a problem. PNG is an image format that
provides lossless compression.
Lossy Data Compression Lossy compression reduces a file by permanently eliminating certain information,
especially redundant information. When the file is uncompressed, only a part of the
original information is still there (although the user may not notice it). Lossy
compression is generally used for video and sound, where a certain amount of
information loss will not be detected by most users. JPEG provides lossy
compression.
Metadata Metadata is data that describes other data. Metadata summarizes basic information
about data, which can make finding and working with particular instances of data
easier. It provides information concerning an item's content such as image
resolution and size.
Parameters* In computer programming, a parameter or "argument" is a value that is passed into
a function. Most modern programming languages allow functions to have multiple
parameters. While the syntax of a function declaration varies between programming
languages, a typical function with two parameters may look something like this:
function graphXY(x, y)
{
...
}
generalize a solution by allowing a procedure to be used instead of duplicate code;
provide different values as input to procedures when they are called in a program.
Pseudocode Pseudocode is a detailed yet readable description of what a computer program or
algorithm must do. It may also describe an operating principle. It is expressed in a
formally-styled natural language rather than in a programming language intended
for humans. The conventions of normal programming continue.
Sequencing The execution of each step/action of an algorithm in the precise order in which the
statements are given.
One of the three building blocks of algorithms. The other two logic structures are
selection and iteration. In a sequence structure, an action, or event, leads to the
next ordered action in a predetermined order. The sequence can contain any
number of actions, but no actions can be skipped in the sequence. The program,
when run, must perform each action in order with no possibility of skipping an action
or branching off to another action.
The term sequence is often applied to video and audio.
Simulations The use of a computer to represent the dynamic responses of one system by the
behavior of another system modeled after it. A simulation uses a mathematical
description, or model, of a real system in the form of a computer program.
Principles Vocabulary 2026
| Key Terms, Study Guide,
Practice Questions,
Answers & Exam Review |
Complete Ethics Study
Guide
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
,Algorithm At its core, an algorithm is really just a generalized, conceptual solution to a
problem that can later be implemented in some real-world form like a computer
program.
Application Program Interface Application program interface (API) is a set of routines, protocols, and tools for
constructing software applications. An API specifies how software components
should interact. In addition, APIs are used when programming graphical user
interface (GUI) components.
Binary A numeric system of base 2 that only uses combinations of the digits zero and one;
this is used in one of the lowest levels of abstraction. Computers operate in binary,
as they store data and perform calculations using only zeros and ones. While a
single binary digit can be used to represent True (1) or False (0) in boolean logic,
multiple binary digits can be used in conjunction to store large numbers and perform
complex functions. Computers translate between binary and what you actually work
with such as numbers and text.
Binary Search A search algorithm that locates the position of a target value within a sorted array by
repeatedly dividing the search interval in half; can only be used when the list is
sorted. Because of its divide-and-conquer approach, the amount of work required to
find an item grows much more slowly with Binary Search than with Sequential
Search. In fact, with this logarithmic behavior
Boolean Function* Any function based on the operations AND, OR, and NOT, and whose elements are
from the domain of Boolean algebra. A function whose arguments, as well as the
function itself, assume values from a two-element set (usually {0,1})
Central Processing Unit CPU, or processor, is the brains of the computer where most calculations take
place. Contains the circuitry necessary to interpret and execute program
instructions.
Computational Artifact Something created by a human using a computer and can be, but is not limited to, a
program, an image, an audio, a video, a presentation, or web page file
Cryptography The science of coding and decoding messages in order to keep them secure.
Coding takes place using a key that ideally is known only by the sender and
intended recipient of the message.
Floating Point Numbers As the name implies, floating point numbers are numbers that contain floating
decimal points. Examples include, the numbers 5.5, 0.001, and -2,345.6789.
Numbers without decimal places are called integers. Computers recognize real
numbers that contain fractions as floating point numbers.
Hexadecimal Hexadecimal describes a base-16 number system. That is, it describes a numbering
system containing 16 sequential numbers as base units (including 0) before adding
a new position for the next number. The hexadecimal numbers are 0-9 and then use
the letters A-F. Used to represent digital data because it utilizes fewer digits than
binary.
Integers An integer is a whole number (not a fraction) that can be positive, negative, or zero.
In computer science, an integer is a datum of integral data type, a data type that
represents some finite subset of the mathematical integers. Integral data types may
be of different sizes and may or may not be allowed to contain negative values.
Iterations Iteration is the repetition of part of an algorithm until a condition is met or for a
specified number of times. This is often called a 'loop'. Recursive functions
repeatedly execute themselves as part of their operation. Upon completing all
instructions and resetting to the first one iteration has been completed.
, Libraries In computer science, a library is a collection of non-volatile resources that a
program can use often to develop software. Libraries are particularly useful for
storing frequently used routines because you do not need to explicitly link them to
every program that uses them. The linker automatically looks in libraries for routines
that it does not find elsewhere. Resources which may be found in libraries include
data, documentation, message templates, pre-written code, classes, or values.
Linear/Sequential Search A process that checks every element in the list sequentially until the desired
element is found or all elements have been searched. Can be used in any type of
list. Has linear performance.
Lossless Data Compression With lossless compression, every single bit of data that was originally in the file
remains after the file is uncompressed. All of the information is completely restored.
This is generally the technique of choice for text or spreadsheet files, where the loss
of words or financial data could pose a problem. PNG is an image format that
provides lossless compression.
Lossy Data Compression Lossy compression reduces a file by permanently eliminating certain information,
especially redundant information. When the file is uncompressed, only a part of the
original information is still there (although the user may not notice it). Lossy
compression is generally used for video and sound, where a certain amount of
information loss will not be detected by most users. JPEG provides lossy
compression.
Metadata Metadata is data that describes other data. Metadata summarizes basic information
about data, which can make finding and working with particular instances of data
easier. It provides information concerning an item's content such as image
resolution and size.
Parameters* In computer programming, a parameter or "argument" is a value that is passed into
a function. Most modern programming languages allow functions to have multiple
parameters. While the syntax of a function declaration varies between programming
languages, a typical function with two parameters may look something like this:
function graphXY(x, y)
{
...
}
generalize a solution by allowing a procedure to be used instead of duplicate code;
provide different values as input to procedures when they are called in a program.
Pseudocode Pseudocode is a detailed yet readable description of what a computer program or
algorithm must do. It may also describe an operating principle. It is expressed in a
formally-styled natural language rather than in a programming language intended
for humans. The conventions of normal programming continue.
Sequencing The execution of each step/action of an algorithm in the precise order in which the
statements are given.
One of the three building blocks of algorithms. The other two logic structures are
selection and iteration. In a sequence structure, an action, or event, leads to the
next ordered action in a predetermined order. The sequence can contain any
number of actions, but no actions can be skipped in the sequence. The program,
when run, must perform each action in order with no possibility of skipping an action
or branching off to another action.
The term sequence is often applied to video and audio.
Simulations The use of a computer to represent the dynamic responses of one system by the
behavior of another system modeled after it. A simulation uses a mathematical
description, or model, of a real system in the form of a computer program.
