📚 AS Cambridge Computer Science: Vocabulary & Terminology Quick Memorization Guide | AS 剑桥计算机科学：词汇术语速记指南
Mastering key terminology is the first step to excelling in AS Cambridge Computer Science. This guide presents essential terms grouped by topic, each explained clearly in English and followed by a Chinese equivalent, making memorisation faster and more reliable.
掌握关键术语是在 AS 剑桥计算机科学中取得好成绩的第一步。本指南按主题分类呈现核心术语，每个术语先用英文清晰解释，再附上中文对应，让记忆更快更牢固。
1. Data Representation | 数据表示
Binary – a base-2 number system using only 0 and 1. All computer data is ultimately stored and processed in binary form.
二进制 – 只使用 0 和 1 的基数为 2 的数制。所有计算机数据最终都以二进制形式存储和处理。
Denary (decimal) – the base-10 number system we use in everyday life, using digits 0–9.
十进制 – 我们日常生活中使用的基数为 10 的数制，使用数字 0 到 9。
Hexadecimal – a base-16 system using digits 0–9 and letters A–F. It is used as a more compact way to represent binary numbers.
十六进制 – 基数为 16 的数制，使用数字 0–9 和字母 A–F。用于更紧凑地表示二进制数。
Bit – the smallest unit of data in a computer, representing a binary digit (0 or 1).
比特 / 位 – 计算机中最小的数据单位，表示一个二进制数字 (0 或 1)。
Byte – a group of 8 bits, typically the smallest addressable unit of memory.
字节 – 由 8 个比特组成，通常是内存中可寻址的最小单位。
Kilobyte (KB) – approximately 1000 bytes (10³ bytes); often used to measure small file sizes.
千字节 – 约 1000 字节 (10³ 字节)，常用于衡量小文件的大小。
Megabyte (MB) – approximately one million bytes (10⁶ bytes).
兆字节 – 约一百万字节 (10⁶ 字节)。
Gigabyte (GB) – approximately one billion bytes (10⁹ bytes); common for memory and storage capacities.
吉字节 – 约十亿字节 (10⁹ 字节)，常用于描述内存和存储容量。
Terabyte (TB) – approximately one trillion bytes (10¹² bytes), used for large-scale storage.
太字节 – 约一万亿字节 (10¹² 字节)，用于大规模存储。
Nibble – a group of 4 bits, equivalent to a single hexadecimal digit.
半字节 / 四位组 – 由 4 个比特组成，相当于一个十六进制数字。
Word – a fixed-sized group of bits handled as a unit by the processor, e.g. 16-bit word, 32-bit word.
字 – 处理器作为一个整体处理的固定大小的比特组，例如 16 位字、32 位字。
Character set – a defined list of characters recognised by the computer, where each character has a unique binary code.
字符集 – 计算机能够识别的字符的确定列表，每个字符对应一个唯一的二进制代码。
ASCII – American Standard Code for Information Interchange; uses 7 or 8 bits to represent common English characters and control codes.
美国信息交换标准码 – 使用 7 位或 8 位表示常用英语字符和控制码。
Unicode – a character set that can represent characters from all major languages and many symbols, using up to 32 bits per character to provide a unique code for every glyph.
统一码 / 万国码 – 能够表示所有主要语言字符和许多符号的字符集，每个字符最多使用 32 位，为每个字形提供唯一编码。
2. Image and Sound Representation | 图像与声音表示
Pixel – the smallest picture element of a bitmap image; each pixel is stored as a binary code for its colour.
像素 – 位图图像中最小的图像元素；每个像素的颜色用二进制编码存储。
Resolution – number of pixels per inch (ppi). Higher resolution gives more detail but larger file size.
分辨率 – 图像中像素的总数 (如宽 × 高) 或每英寸像素数 (ppi)。分辨率越高细节越多，但文件也越大。
Colour depth – epth allows more colours to be represented. For example, 8-bit colour depth = 256 colours.
颜色深度 – 表示每个像素颜色所使用的位数。颜色深度越高，能表示的颜色越多。例如 8 位颜色深度 = 256 种颜色。
Metadata for images – extra data stored with an image, such as width, height, colour depth, and resolution, needed to interpret the pixel data correctly.
图像元数据 – 随图像一起存储的额外数据，如宽度、高度、颜色深度和分辨率，用于正确解读像素数据。
Sampling (sound) – the process of measuring the amplitude of a sound wave at discrete time intervals. The sampling rate is measured in Hz; e.g. 44.1 kHz means 44,100 samples per second.
采样 (声音) – 在离散时间点测量声波振幅的过程。采样率以 Hz 为单位；例如 44.1 kHz 表示每秒 44,100 个采样点。
Sampling resolution (bit depth) – the number of bits used to record the amplitude of each sound sample. E.g. 16-bit sampling resolution provides 65,536 possible amplitude levels.
采样分辨率 (位深度) – 记录每个声音样本振幅所使用的位数。例如 16 位采样分辨率可提供 65,536 级振幅。
Bit rate (sound) – pling resolution × number of channels. Higher bit rate usually means better audio quality.
比特率 (声音) – 每秒处理的比特数，计算公式：采样率 × 采样分辨率 × 声道数。比特率越高通常音频质量越好。
3. Compression | 压缩技术
Compression – reducing the size of a file so that it takes up less storage space or can be transmitted faster.
压缩 – 减少文件大小，使其占用更少的存储空间或更快传输。
Lossy compression – reduces file size by permanently discarding some data, often from areas less perceptible to humans. Used for JPEG images, MP3 audio, and MPEG video. The original data cannot be perfectly restored.
有损压缩 – 通过永久丢弃部分数据 (通常是人类不易察觉的部分) 来减小文件大小。用于 JPEG 图像、MP3 音频和 MPEG 视频。原始数据无法完全恢复。
Lossless compression – reduces file size without losing any information, so the original data can be reconstructed exactly. Examples include ZIP files, PNG images, and run-length encoding.
无损压缩 – 在不丢失任何信息的情况下减小文件大小，原始数据可完整重建。例如 ZIP 文件、PNG 图像和行程长度编码。
Run-length encoding (RLE) – a lossless compression method where consecutive identical pixels are stored as one data value and a count, e.g. '4 red' instead of four separate 'red' pixels.
行程长度编码 – 一种无损压缩方法，将连续相同的像素存储为一个数据值和一个计数，例如用 '4 红' 代替四个独立的 '红' 像素。
Huffman coding – a lossless compression technique that assigns shorter binary codes to frequently occurring symbols and longer codes to infrequent ones, based on building a binary tree.
霍夫曼编码 – 一种无损压缩技术，基于构建二叉树，为频繁出现的符号分配较短的二进制码，为不常见的符号分配较长的码。
4. Networking Basics | 网络基础
LAN (Local Area Network) – a network that connects computers in a small geographical area, such as an office or school, using cables or Wi-Fi.
局域网 – 覆盖较小地理区域 (如办公室或学校) 的网络，通过电缆或 Wi-Fi 连接计算机。
WAN (Wide Area Network) – a network that connects computers over a large geographical area, often using public infrastructure like telephone lines or satellites. The internet is a WAN.
广域网 – 覆盖大地理区域的网络，通常使用电话线或卫星等公共基础设施。互联网就是一个广域网。
WLAN (Wireless Local Area Network) – a LAN that uses wireless connections, typically Wi-Fi, to connect devices within a limited area.
无线局域网 – 使用无线连接 (通常是 Wi-Fi) 在有限区域内连接设备的局域网。
Network interface card (NIC) – hardware that connects a device to a network. It has a unique MAC address.
网络接口卡 – 将设备连接到网络的硬件。它具有唯一的 MAC 地址。
MAC address – a unique 48-bit hardware address assigned to each NIC, usually written in hexadecimal. It is used within a local network.
MAC 地址 – 每个网络接口卡独有的 48 位硬件地址，通常用十六进制书写。用于局域网内部。
Router – a device that forwards data packets between different networks, using IP addresses to determine the best path.
路由器 – 在不同网络之间转发数据包的设备，使用 IP 地址来确定最佳路径。
Switch – a networking device that connects devices within a LAN and uses MAC addresses to forward data frames to the correct destination port.
交换机 – 在局域网内连接设备的网络设备，使用 MAC 地址将数据帧转发到正确的目标端口。
Commutation methods: circuit switching vs packet switching – circuit switching establishes a dedicated physical path for the duration of a call (used in traditional telephony), while packet switching breaks data into packets that travel independently (used in modern networks).
交换方式：电路交换与分组交换 – 电路交换在整个通话期间建立专用的物理通路 (用于传统电话)，而分组交换将数据拆分为独立传输的数据包 (用于现代网络)。
5. Protocols and Addresses | 协议与地址
Protocol – a set of rules that govern how data is transmitted and received between devices.
协议 – 一组管理数据在设备之间传输和接收的规则。
IP address – a logical address used to identify a device on a network. IPv4 uses 32 bits written as four dotted decimal numbers; IPv6 uses 128 bits, written in hexadecimal groups separated by colons.
IP 地址 – 用于标识网络设备的逻辑地址。IPv4 使用 32 位，写作点分十进制四组数；IPv6 使用 128 位，以冒号分隔的十六进制组表示。
URL (Uniform Resource Locator) – a human-readable address that identifies a resource on the web, containing protocol, domain name, and path.
统一资源定位符 – 一个人类可读的地址，用于标识网络上的资源，包含协议、域名和路径。
DNS (Domain Name System) – the internet service that translates domain names (like www.example.com) into IP addresses.
域名系统 – 将域名 (如 www.example.com) 转换为 IP 地址的互联网服务。
HTTP (Hypertext Transfer Protocol) – the protocol used to transfer web pages over the internet. It sends data in plain text and is not secure.
超文本传输协议 – 用于在互联网上传输网页的协议。它以明文方式发送数据，不安全。
HTTPS – a secure version of HTTP that uses SSL/TLS encryption to protect data in transit.
安全超文本传输协议 – HTTP 的安全版本，使用 SSL/TLS 加密保护传输中的数据。
FTP (File Transfer Protocol) – a protocol used for transferring files between computers over a network.
文件传输协议 – 用于在网络上计算机之间传输文件的协议。
TCP/IP (Transmission Control Protocol / Internet Protocol) – a suite of protocols that enables communication across the internet. TCP ensures reliable delivery through error checking and sequencing; IP handles addressing and routing of packets.
传输控制协议 / 互联网协议 – 一组支持互联网通信的协议。TCP 通过差错校验和排序确保可靠传输；IP 处理数据包的寻址和路由。
6. Computer Architecture | 计算机体系结构
CPU (Central Processing Unit) – the component that executes instructions and processes data; often called the 'brain' of the computer.
中央处理器 – 执行指令和处理数据的组件，常被称为计算机的 '大脑'。
ALU (Arithmetic Logic Unit) – part of the CPU that performs arithmetic and logical operations.
算术逻辑单元 – CPU 中执行算术和逻辑运算的部分。
CU (Control Unit) – the part of the CPU that manages the execution of instructions by sending control signals to other components.
控制单元 – CPU 中通过向其他部件发送控制信号来管理指令执行的部分。
Registers – small, extremely fast storage locations inside the CPU. Examples: Program Counter (PC), Memory Address Register (MAR), Memory Data Register (MDR), Current Instruction Register (CIR), Accumulator (ACC).
寄存器 – CPU 内部容量小、速度极快的存储位置。例如：程序计数器 (PC)、内存地址寄存器 (MAR)、内存数据寄存器 (MDR)、当前指令寄存器 (CIR)、累加器 (ACC)。
Fetch-decode-execute cycle – the process by which the CPU retrieves an instruction from memory, interprets it, and then carries it out. This cycle repeats continuously.
取指 - 译码 - 执行循环 – CPU 从内存取出指令、解释指令然后执行的过程。此循环不断重复。
Buses – sets of parallel wires that transfer data, addresses, and control signals between components. The three main buses are: address bus, data bus, and control bus.
总线 – 在组件之间传输数据、地址和控制信号的并行线路。三个主要总线：地址总线、数据总线和控制总线。
Clock speed – the number of cycles the CPU can perform per second, measured in GHz (gigahertz). A higher clock speed means more instructions can be executed per second.
时钟频率 – CPU 每秒可以执行的周期数，以 GHz (吉赫兹) 为单位。时钟频率越高，每秒可执行的指令越多。
Cores – individual processing units within a CPU. Multiple cores allow parallel processing of instructions.
核心 – CPU 内部的独立处理单元。多个核心可实现指令的并行处理。
Cache – a small amount of very fast memory close to the CPU, used to temporarily store frequently accessed data and instructions.
高速缓存 – 靠近 CPU 的少量极快内存，用于临时存储频繁访问的数据和指令。
Embedded system – a computer system designed for a dedicated function within a larger machine, often with limited resources. Examples: washing machine controller, microwave oven, car engine management system.
嵌入式系统 – 为大型机器中的特定功能而设计的计算机系统，通常资源有限。例如：洗衣机控制器、微波炉、汽车发动机管理系统。
7. Operating Systems and Software | 操作系统与软件
Operating system (OS) – system software that manages hardware resources, provides a user interface, and enables applications to run. Examples: Windows, Linux, macOS.
操作系统 – 管理硬件资源、提供用户界面并支持应用程序运行的系统软件。例如：Windows、Linux、macOS。
Kernel – the core part of the OS that manages memory, processes, and hardware access, running in a privileged mode.
内核 – 操作系统的核心部分，管理内存、进程和硬件访问，以特权模式运行。
Graphical User Interface (GUI) – allows users to interact with the computer using visual elements like windows, icons, and menus.
图形用户界面 – 允许用户通过窗口、图标和菜单等可视化元素与计算机交互。
Command-line interface (CLI) – a text-based interface where users type commands to perform tasks.
命令行界面 – 用户通过键入命令来执行任务的基于文本的界面。
Utility software – programs that perform specific tasks related to managing and maintaining the computer system, such as antivirus, backup, disk defragmentation, and file compression tools.
实用工具软件 – 执行与管理和维护计算机系统相关的特定任务的程序，如防病毒、备份、磁盘碎片整理和文件压缩工具。
Compiler – a program that translates high-level source code into machine code all at once, producing a standalone executable file.
编译器 – 一次性将高级源代码翻译成机器代码，并生成独立的可执行文件的程序。
Interpreter – a program that translates high-level source code line by line, executing each line immediately without producing a permanent object file.
解释器 – 逐行翻译高级源代码，立即执行每行，不产生永久目标文件的程序。
Assembler – a program that translates assembly language (low-level) into machine code.
汇编器 – 将汇编语言 (低级) 翻译成机器代码的程序。
8. Security Threats | 安全威胁
Malware – malicious software designed to disrupt, damage, or gain unauthorised access to a computer system.
恶意软件 – 旨在破坏、损害或未经授权访问计算机系统的恶意软件。
Virus – a type of malware that attaches itself to a legitimate program or file and spreads when that program is executed.
病毒 – 一种将自身附加到合法程序或文件上，并在该程序执行时传播的恶意软件。
Worm – a standalone malware that replicates itself to spread to other computers, often exploiting network vulnerabilities.
蠕虫 – 一种独立的恶意软件，自我复制以扩散到其他计算机，通常利用网络漏洞。
Trojan horse – malware disguised as useful or legitimate software to trick users into installing it.
特洛伊木马 – 伪装成有用或合法软件的恶意软件，欺骗用户安装。
Spyware – software that secretly collects user information without consent, such as browsing habits or personal data.
间谍软件 – 未经同意秘密收集用户信息 (如浏览习惯或个人数据) 的软件。
Adware – software that automatically displays or downloads unwanted advertisements. Some adware may include spyware features.
广告软件 – 自动显示或下载不需要的广告的软件。有些广告软件可能包含间谍软件功能。
Ransomware – malware that encrypts the victim's data and demands payment (a ransom) to restore access.
勒索软件 – 对受害者的数据进行加密并要求支付赎金以恢复访问的恶意软件。
Phishing – a social engineering attack using fraudulent emails or websites to trick individuals into revealing sensitive information like passwords or credit card details.
网络钓鱼 – 使用欺诈性电子邮件或网站来诱骗个人泄露密码或信用卡信息等敏感数据的社会工程学攻击。
Pharming – a cyberattack that redirects a website's traffic to a fake site, often by manipulating DNS settings or host files.
域欺诈 – 通过操纵 DNS 设置或主机文件，将网站流量重定向到虚假网站的网络攻击。
Denial of Service (DoS) – an attack that floods a server or network with excessive requests, making it unavailable to legitimate users.
拒绝服务攻击 – 通过向服务器或网络发送过量的请求使其不堪重负，导致合法用户无法使用。
Firewall – a security system that monitors and controls incoming and outgoing network traffic based on predetermined rules, protecting the network from unauthorised access.
防火墙 – 根据预设规则监控和控制进出网络流量的安全系统，保护网络免受未经授权的访问。
9. Encryption and Authentication | 加密与认证
Encryption – the process of converting plaintext into ciphertext using an algorithm and a key, so that only authorised parties can read it.
加密 – 使用算法和密钥将明文转换为密文的过程，只有授权方才能读取。
Symmetric encryption – uses the same key for both encryption and decryption. It is fast but requires the key to be shared securely. Examples: AES, DES.
对称加密 – 加密和解密使用相同的密钥。速度快，但需要安全地共享密钥。例如：AES、DES。
Asymmetric encryption – uses a pair of keys: a public key for encryption and a private key for decryption. The public key can be openly distributed, while the private key is kept secret. Examples: RSA.
非对称加密 – 使用一对密钥：公钥用于加密，私钥用于解密。公钥可公开分发，私钥则保密。例如：RSA。
Digital signature – a cryptographic method used to verify the authenticity and integrity of a digital message or document. The sender signs with their private key, and the recipient verifies using the sender's public key.
数字签名 – 用于验证数字消息或文档的真实性和完整性的加密方法。发送者用私钥签名，接收者用发送者的公钥验证。
SSL/TLS – Secure Sockets Layer / Transport Layer Security are protocols that provide secure communication over a network by encrypting data, often used in HTTPS. They use a combination of symmetric and asymmetric encryption.
安全套接层 / 传输层安全 – 通过加密数据在网络上提供安全通信的协议，常用于 HTTPS。它们结合使用了对称和非对称加密。
10. Data, Databases and Ethics | 数据、数据库与道德规范
Database – a structured collection of data held in a computer system, allowing efficient storage, retrieval, and management.
数据库 – 计算机系统中结构化的数据集合，支持高效的存储、检索和管理。
Table – a collection of related data organised in rows and columns. Each table typically represents one entity.
表 – 按行和列组织的相关数据集合。每个表通常代表一个实体。
Record – a single row in a table, containing all the data about one specific item.
记录 – 表中的一行，包含关于一个特定项目的所有数据。
Field – a single column in a table, containing a specific type of data for each record.
字段 – 表中的一列，包含每条记录中特定类型的数据。
Primary key – a field (or combination) that uniquely identifies each record in a table. It cannot be null and must be unique.
主键 – 唯一标识表中每条记录的字段 (或组合)。它不能为空，必须唯一。
Foreign key – a field in one table that refers to the primary key in another table, used to link tables together.
外键 – 一个表中引用另一表主键的字段，用于将表关联在一起。
SQL (Structured Query Language) – a language used to query, manipulate, and manage relational databases.
结构化查询语言 – 用于查询、操作和管理关系数据库的语言。
Copyright – the legal right that protects the creator's original work from being used without permission.
版权 – 保护创作者原创作品不被未经许可使用的法律权利。
Plagiarism – presenting someone else's work or ideas as your own without proper acknowledgment.
剽窃 – 将他人作品或思想当作自己的，且不给予适当承认的行为。
Open-source software – software whose source code is made publicly available, which can be modified and shared under specific licences.
开源软件 – 源代码公开发布的软件，可在特定许可证下修改和共享。
Proprietary software – software owned by an individual or company, where the source code is kept secret and distribution is restricted.
专有软件 – 由个人或公司拥有的软件，源代码保密，分发受限。
Freeware – software that is available at no cost but usually remains proprietary; source code is not provided.
免费软件 – 不收费的软件，但通常仍是专有的，不提供源代码。
Shareware – software distributed for free on a trial basis, with payment required for continued use or full features.
共享软件 – 以试用方式免费分发的软件，继续使用或获取全部功能需付费。
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