Computing Systems & Networks: every key term you need (+ practice quiz)

More AP Computer Science Principles guides

• Data & Representation
• Algorithms & Programming
• Programming & Modeling
• Impact of AI & Computing

Computing

Using computational tools to solve problems, create solutions, and explore ideas.

Algorithm

Step-by-step procedure for solving a problem or accomplishing a task.

Program

Sequence of instructions written in a programming language to accomplish goals.

Hardware

Physical components of a computer system: CPU, memory, storage, input/output.

Software

Programs and operating systems that run on computing devices.

Data

Information represented in digital form: numbers, text, images, audio, video.

Binary

Number system using only 0 and 1; foundation for all digital computing.

Bit

Single binary digit; smallest unit of digital information.

Byte

8 bits grouped together; basic unit for storing and transmitting data.

Storage

Devices that permanently hold data: hard drives, SSDs, cloud servers.

Memory

Temporary storage used by CPU during processing; faster than disk storage.

Processing Power

Speed at which a computer performs operations; measured in GHz.

Network

Connected computers sharing data and resources through communication lines.

Internet

Global system of interconnected networks enabling worldwide communication.

Protocol

Set of rules governing how devices communicate and exchange data.

Boolean

System using true/false values; foundation for logical operations.

Variable

Named container storing data value that can change during program execution.

Syntax

Rules governing structure and format of statements in a programming language.

Packet

A small chunk of data plus metadata (addresses, sequence number) sent independently across the Internet and reassembled at the destination.

Routing

The process of finding a path for a packet from sender to receiver; routers choose next hops dynamically, so packets from one message can take different paths.

Redundancy

Having multiple paths between devices so the network keeps working when a link or router fails; a key reason the Internet is fault tolerant.

Fault Tolerance

A system's ability to keep operating correctly when some components fail, achieved on the Internet through redundant connections and rerouting.

IP (Internet Protocol)

Protocol that assigns addresses to devices and specifies how packets are addressed and routed between networks.

TCP

Transmission Control Protocol; guarantees reliable, in-order delivery by acknowledging packets and retransmitting lost ones.

UDP

User Datagram Protocol; sends packets without delivery guarantees, trading reliability for lower latency in streaming and gaming.

HTTP / HTTPS

Application-layer protocol used by web browsers to request pages; HTTPS wraps it in encryption via TLS.

DNS

Domain Name System; translates human-readable names such as example.org into IP addresses.

Bandwidth

Maximum amount of data a connection can transfer per unit time, typically measured in bits per second.

Latency

Time it takes a packet to travel from sender to receiver, distinct from bandwidth.

Scalability

Property that lets the Internet grow by adding new devices and networks without redesigning the whole system, enabled by open protocols and hierarchical addressing.

Sequential Computing

Operations execute one after another; total time is the sum of all operation times.

Parallel Computing

A program is broken into pieces that run simultaneously on multiple processors; speedup is limited by the sequential portion.

Distributed Computing

Multiple networked devices cooperate on one problem, allowing larger inputs and more storage than a single machine.

Speedup

Ratio of sequential run time to parallel run time for the same task; a speedup of 2 means the parallel version takes half as long.

Open Standard

A publicly documented protocol that any vendor can implement, which is why devices from different companies interoperate on the Internet.

IPv6

Newer version of IP using 128-bit addresses to replace the exhausted 32-bit IPv4 address space.