📚 Edexcel GCSE Computer Science Vocabulary Memory Guide | Edexcel GCSE 计算机词汇术语速记指南
Mastering the precise vocabulary of computer science is just as important as understanding the concepts themselves. This guide clusters key Edexcel GCSE terms into logical groups, providing crisp English definitions followed instantly by their Chinese equivalents, helping you build a bilingual mental map of all the terminology that can appear in your examinations.
掌握计算机科学的精确词汇与理解概念本身同样重要。本指南将 Edexcel GCSE 核心术语按逻辑分组，用清晰英文定义与紧跟的中文对等表达帮助你构建双语思维导图，覆盖考试中可能出现的全部术语。
1. Algorithms and Computational Thinking | 算法与计算思维
An algorithm is a step‑by‑step sequence of instructions that solves a specific problem; it must be unambiguous, finite and have clearly defined inputs and outputs. Computational thinking, on the other hand, is the mental toolkit of abstraction, decomposition and pattern recognition used to design such algorithms.
算法是解决特定问题的一系列分步指令；它必须明确、有限并具有清晰定义的输入和输出。计算思维则是用于设计算法的抽象、分解和模式识别的心智工具包。
Decomposition means breaking a complex problem into smaller, more manageable sub‑problems. Abstraction involves focusing only on the essential details while ignoring irrelevant information to create a simplified model.
分解指将一个复杂问题拆分成更小、更易管理的子问题。抽象则指只关注基本细节，忽略无关信息，从而建立一个简化模型。
Pseudocode is a text‑based design notation that resembles a simplified programming language; it is used to plan algorithms without worrying about syntax rules of a specific language. A flowchart uses standard symbols (ovals for start/end, parallelograms for input/output, rectangles for processes) to represent the flow of an algorithm visually.
伪代码是一种基于文本的设计标记，类似于简化的编程语言，用于规划算法而不必担心特定语言的语法规则。流程图使用标准符号（椭圆形表示开始/结束，平行四边形表示输入/输出，矩形表示处理过程）来可视化算法的流程。
2. Data Types and Variables | 数据类型与变量
A variable is a named memory location that stores a value which can change while the program is running. In contrast, a constant is a named container whose value is fixed once initialized — it cannot be altered during execution, making programs more readable and less error‑prone.
变量是一个命名的内存位置，存储程序运行期间可改变的值。常量则是一个命名的容器，一旦初始化其值便固定——执行期间不可更改，使程序更易读并减少错误。
The five fundamental data types you must know are: integer (whole numbers, e.g. 17, -4), real/float (numbers with a fractional part, e.g. 3.14), Boolean (True or False), character (a single symbol like ‘A’, ‘7’, ‘?’) and string (a sequence of characters, e.g. ‘hello’).
必须掌握的五种基本数据类型是：整型（整数，如 17、-4）、实型/浮点型（含小数部分，如 3.14）、布尔型（True 或 False）、字符型（单个符号，如 ‘A’、’7’、’?’）和字符串（字符序列，如 ‘hello’）。
Casting converts one data type into another, for example converting an integer to a string for concatenation. String manipulation operations include concatenation (joining strings), slicing (extracting part of a string) and finding length.
类型转换将一种数据类型转为另一种，例如将整型转为字符串以便拼接。字符串操作包括拼接（连接字符串）、切片（提取字符串的一部分）和求长度。
3. Control Structures: Sequence, Selection, Iteration | 控制结构：顺序、选择、迭代
Programs execute in sequence by default — one statement after another, in the order written. Selection allows the program to make decisions: an if statement executes a block of code only if a condition evaluates to True; an if‑else provides an alternative block when the condition is False.
程序默认按顺序执行——按编写的顺序逐条执行。选择使程序能够做出决策：if 语句仅在条件为 True 时执行代码块；if‑else 则在条件为 False 时提供备选块。
For more complex branching, switch/case or nested if structures can test multiple values of a single variable. Iteration repeats a block of code: count‑controlled loops like FOR repeat a set number of times, while condition‑controlled loops like WHILE continue as long as a condition remains True.
对于更复杂的分支，switch/case 或嵌套 if 结构可测试单个变量的多个取值。迭代重复执行代码块：计数控制循环如 FOR 重复固定次数，条件控制循环如 WHILE 则只要条件为 True 就继续执行。
Be careful to avoid infinite loops — situations where the terminating condition is never met. A REPEAT…UNTIL loop tests the condition at the end, guaranteeing the block runs at least once.
注意避免无限循环——即终止条件永远达不到的情况。REPEAT…UNTIL 循环在末尾测试条件，保证代码块至少执行一次。
4. Subprograms: Functions and Procedures | 子程序：函数与过程
A subprogram is a named block of code that performs a specific task, promoting modularity and reusability. Procedures are subprograms that carry out actions but do not return a value; functions always return a value and can be used inside expressions.
子程序是一个命名代码块，执行特定任务，促进模块化和可重用性。过程是执行操作但不返回值的子程序；函数始终返回一个值，并可在表达式中使用。
Parameters are placeholders in the subprogram definition that receive input values when the subprogram is called. Arguments are the actual values passed during the call. Parameters enable generality — the same logic works with different data.
参数是子程序定义中的占位符，在调用子程序时接收输入值。实参是调用时传递的实际值。参数实现了通用性——相同的逻辑可以处理不同的数据。
Variables declared inside a subprogram are local variables — they exist only during the subprogram’s execution and are inaccessible from outside. Global variables are declared in the main program and can be accessed and modified by any subprogram, though their overuse can lead to confusing side effects.
在子程序内部声明的变量是局部变量——它们仅存在于子程序执行期间，外部不可访问。全局变量在主程序中声明，任何子程序都可以访问和修改，但过度使用可能导致混乱的副作用。
5. Data Representation: Binary, Hex and Storage | 数据表示：二进制、十六进制与存储
Computers use binary (base‑2) because transistors have two stable states — off (0) and on (1). A single binary digit is a bit; 8 bits form a byte. Nibble is a group of 4 bits. Hexadecimal (base‑16) uses digits 0‑9 and letters A‑F, providing a more compact way to represent binary — one hex digit stands for exactly four bits.
计算机使用二进制（基数为 2），因为晶体管有两种稳定状态——关（0）和开（1）。一个二进制位称为比特；8 比特构成一个字节。半字节是 4 比特组。十六进制（基数为 16）使用 0‑9 和 A‑F，提供更紧凑的二进制表示——一位十六进制数字精确代表 4 位二进制。
Overflow occurs when the result of a calculation exceeds the available number of bits, leading to wrapping or errors. Binary addition follows simple rules: 0+0=0, 1+0=1, 1+1=0 carry 1, 1+1+1=1 carry 1. Two’s complement is a method for representing negative numbers.
当计算结果超出可用位数时发生溢出，导致回绕或错误。二进制加法遵循简单规则：0+0=0，1+0=1，1+1=0 进 1，1+1+1=1 进 1。补码是表示负数的一种方法。
Images are stored as a grid of pixels, each assigned a binary colour value — higher colour depth (bits per pixel) gives more colours. Sound is sampled thousands of times per second; sample rate (Hz) and bit depth determine the quality. ASCII uses 7 or 8 bits to represent characters, while Unicode extends this to cover global scripts.
图像以像素网格存储，每个像素赋予一个二进制颜色值——颜色深度（每像素位数）越高，颜色越多。声音每秒采样数千次；采样率（Hz）和位深度决定音质。ASCII 使用 7 或 8 比特表示字符，Unicode 则将其扩展到涵盖全球文字。
6. Computer Architecture: CPU and Memory | 计算机体系结构：CPU 与内存
The Central Processing Unit (CPU) is the brain of the computer; it follows the fetch‑decode‑execute cycle. The Control Unit (CU) directs the flow of data and instructions, while the Arithmetic Logic Unit (ALU) performs calculations and logical operations. Registers are ultra‑fast memory locations inside the CPU — key ones include the Program Counter (PC), Memory Address Register (MAR), Memory Data Register (MDR) and Accumulator.
中央处理器（CPU）是计算机的大脑；它遵循取指‑译码‑执行周期。控制单元（CU）指挥数据和指令的流动，算术逻辑单元（ALU）执行计算和逻辑操作。寄存器是 CPU 内部超快的内存位置——关键寄存器包括程序计数器（PC）、内存地址寄存器（MAR）、内存数据寄存器（MDR）和累加器。
RAM (Random Access Memory) is volatile working memory that stores data and programs currently in use; its contents are lost when power is switched off. ROM (Read Only Memory) is non‑volatile and typically stores the boot program (BIOS). Cache is a small, very fast memory located close to the CPU that temporarily stores frequently accessed instructions to reduce the average memory access time.
RAM（随机存取存储器）是易失性工作内存，存储当前正在使用的数据和程序；断电后内容丢失。ROM（只读存储器）是非易失性的，通常存储引导程序（BIOS）。缓存是位于 CPU 附近的小容量高速存储器，临时存放频繁访问的指令以降低平均内存访问时间。
Secondary storage holds data permanently. Magnetic hard disks (HDD) offer large capacity at low cost; solid‑state drives (SSD) use flash memory, are faster, more durable but more expensive per GB. Virtual memory uses part of the hard disk as if it were RAM when physical RAM is full, but this slows performance because disk access is much slower.
辅助存储器永久保存数据。磁性硬盘（HDD）以低成本提供大容量；固态盘（SSD）使用闪存，更快、更耐用，但每 GB 成本更高。虚拟内存当物理 RAM 满时借用硬盘的一部分当作 RAM，但由于磁盘访问慢得多，会降低性能。
7. Networks and Protocols | 网络与协议
A network is two or more devices connected to share resources and data. A LAN (Local Area Network) covers a small geographical area, often using Ethernet or Wi‑Fi; a WAN (Wide Area Network) connects LANs over large distances, using infrastructure like telephone lines or satellites — the Internet is the largest WAN.
网络是指两台或更多设备连接在一起以共享资源和数据。LAN（局域网）覆盖小地理范围，常使用以太网或 Wi‑Fi；WAN（广域网）连接远距离的多个 LAN，使用电话线或卫星等基础设施——互联网是最大的 WAN。
A protocol is an agreed set of rules that govern how data is transmitted between devices. TCP/IP is the foundation suite: TCP breaks data into packets and reassembles them, guaranteeing reliable delivery; IP handles addressing and routing so packets find their destination. HTTP transfers web pages, while HTTPS adds encryption for security. FTP is used for file transfers, SMTP for sending emails and IMAP/POP3 for receiving them.
协议是一套约定的规则，管控设备间数据传输的方式。TCP/IP 是基础协议栈：TCP 将数据拆分成数据包并重组，保证可靠交付；IP 负责寻址和路由，使数据包到达目的地。HTTP 传输网页，HTTPS 通过加密增加安全性。FTP 用于文件传输，SMTP 发送邮件，IMAP/POP3 接收邮件。
Network hardware includes routers (direct packets between networks), switches (connect devices within a LAN and filter traffic based on MAC addresses), and NICs (Network Interface Cards that give a device a physical connection). MAC addresses are unique identifiers hard‑coded into each NIC; IP addresses are logical addresses that can change.
网络硬件包括路由器（在网络之间定向数据包）、交换机（连接 LAN 内的设备并根据 MAC 地址过滤流量）和 NIC（网卡，为设备提供物理连接）。MAC 地址是硬编码在每个 NIC 中的唯一标识符；IP 地址是可改变的逻辑地址。
8. Cybersecurity Threats and Prevention | 网络安全威胁与防范
Malware is malicious software designed to damage or disrupt systems. A virus attaches itself to a legitimate program and spreads when that program is run. A worm self‑replicates across networks without needing a host file. A Trojan horse disguises itself as useful software but delivers a malicious payload.
恶意软件是旨在损害或干扰系统的恶意程序。病毒附着在合法程序上，当该程序运行时传播。蠕虫无需宿主文件即可在网络上自我复制。特洛伊木马伪装成有用软件，却携带恶意负载。
Phishing uses fraudulent emails or websites that appear trustworthy to trick users into revealing sensitive data like passwords or credit card numbers. Social engineering exploits human psychology rather than technical vulnerabilities — for example, pretexting or baiting. A brute‑force attack tries every possible password combination until it finds the correct one.
网络钓鱼使用看似可信的欺诈性邮件或网站引诱用户泄露密码或信用卡号等敏感数据。社会工程利用人的心理而非技术漏洞——例如借口或利诱。暴力攻击尝试所有可能的密码组合直到找到正确的那一个。
Encryption scrambles data into ciphertext using an algorithm and a key, ensuring that even if intercepted, the data remains unreadable without the key. Symmetric encryption uses the same key for encryption and decryption; asymmetric (public‑key) encryption uses a pair — a public key to encrypt and a private key to decrypt. A firewall monitors incoming and outgoing network traffic based on predetermined security rules.
加密使用算法和密钥将数据打乱成密文，确保即使被截获也无法读取。对称加密使用相同密钥加密和解密；非对称（公钥）加密使用一对密钥——公钥加密，私钥解密。防火墙基于预定安全规则监控传入和传出的网络流量。
9. Databases and SQL | 数据库与 SQL
A database is an organised collection of data stored electronically. In a relational database, data is kept in tables — each table is a grid of records (rows) and fields (columns). A flat‑file database is a single table; relational databases link multiple tables using keys to reduce data redundancy.
数据库是以电子方式存储的有组织的数据集合。在关系数据库中，数据存储于表中——每张表是一个由记录（行）和字段（列）组成的网格。平面文件数据库是单张表；关系数据库使用键将多张表链接起来，以减少数据冗余。
A primary key is a field that uniquely identifies each record in a table — it must be unique and not null. A foreign key is a field in one table that refers to the primary key of another table, establishing a relationship between the two. Queries written in SQL (Structured Query Language) retrieve and manipulate data.
主键是唯一标识表中每条记录的字段——必须唯一且非空。外键是一张表中引用另一张表主键的字段，在两表之间建立关系。使用 SQL（结构化查询语言）编写的查询可检索和操作数据。
Essential SQL commands: SELECT fields FROM table WHERE condition ORDER BY field; INSERT INTO table VALUES (…); UPDATE table SET field=value WHERE condition; DELETE FROM table WHERE condition. A * can select all columns. Conditions use operators like =, <, >, AND, OR, LIKE for patterns.
基本 SQL 命令：SELECT 字段 FROM 表 WHERE 条件 ORDER BY 字段；INSERT INTO 表 VALUES (…)；UPDATE 表 SET 字段=值 WHERE 条件；DELETE FROM 表 WHERE 条件。* 可选中所有列。条件使用 =, <, >, AND, OR, LIKE（用于模式匹配）等运算符。
10. Ethical, Legal and Environmental Issues | 伦理、法律与环境问题
The Data Protection Act 2018 governs how personal data may be collected, stored and used; it gives individuals rights (e.g. the right to access their data) and places obligations on data controllers. The Computer Misuse Act 1990 makes it illegal to gain unauthorised access to computer material (hacking), with severe penalties for further malicious intents.
《2018 年数据保护法》规范个人数据的收集、存储和使用方式；它赋予个人权利（如访问其数据的权利），并规定数据控制者的义务。《1990 年计算机滥用法》将未经授权访问计算机资料（黑客行为）定为非法，且对进一步的恶意企图施以严厉惩罚。
The Copyright, Designs and Patents Act protects intellectual property including software code, music and videos. Using proprietary software without a licence is illegal. Open‑source software, however, comes with a licence that allows users to view, modify and share the source code — it promotes collaboration but may lack dedicated support.
《版权、设计和专利法》保护包括软件代码、音乐和视频在内的知识产权。无证使用专有软件是违法的。然而，开源软件附带许可证，允许用户查看、修改和共享源代码——它促进协作，但可能缺少专门支持。
Environmental concerns include the energy consumption of data centres, e‑waste from discarded devices, and the carbon footprint of manufacturing. The ‘digital divide’ refers to the gap between those who have access to modern digital technologies and those who do not. Ethical considerations involve privacy, surveillance, algorithmic bias and the responsibility of technology companies.
环境问题包括数据中心的能耗、废弃设备产生的电子垃圾以及制造过程的碳足迹。“数字鸿沟”指能访问现代数字技术的人群与不能访问的人群之间的差距。伦理考量涉及隐私、监控、算法偏见和科技公司的责任。
11. Software Development Lifecycle | 软件开发周期
The software development lifecycle (SDLC) is a structured process that includes stages: analysis (understanding the problem and requirements), design (planning the solution with diagrams, pseudocode), implementation (writing and compiling code), testing (checking the program works as intended) and evaluation (assessing whether the original requirements are met).
软件开发生命周期（SDLC）是一个结构化过程，包括以下阶段：分析（理解问题与需求）、设计（用图表、伪代码规划解决方案）、实现（编写和编译代码）、测试（检查程序是否按预期工作）和评估（评估是否满足了原始需求）。
Testing is critical: iterative testing checks small sections during development; final/terminal testing checks the whole program. Normal data (valid, expected values), boundary data (values at the edges of acceptable ranges) and erroneous data (invalid inputs) must all be tested. A syntax error is a mistake in the language rules; a logic error produces an unexpected outcome even though the code runs.
测试至关重要：迭代测试在开发过程中检查小片段；最终测试检查整个程序。正常数据（有效、预期值）、边界数据（可接受范围边缘的值）和错误数据（无效输入）都必须测试。语法错误是语言规则错误；逻辑错误即使代码能运行也会产生意外结果。
An Integrated Development Environment (IDE) provides tools to help programmers: a code editor with syntax highlighting, a debugger for stepping through code and inspecting variables, and a compiler or interpreter to translate code into machine language. A compiler translates the entire source code at once into an executable file; an interpreter translates and executes line by line.
集成开发环境（IDE）提供帮助程序员的工具：具有语法高亮的代码编辑器、用于单步执行代码和检查变量的调试器，以及将代码翻译成机器语言的编译器或解释器。编译器一次性将整个源代码翻译成可执行文件；解释器逐行翻译并执行。
12. Boolean Logic and Truth Tables | 布尔逻辑与真值表
Boolean logic uses TRUE and FALSE values, represented by 1 and 0 in digital circuits. The three fundamental logic gates are: AND (output is 1 only if both inputs are 1), OR (output is 1 if at least one input is 1), and NOT (a single‑input gate that inverts the signal: 1 becomes 0, 0 becomes 1).
布尔逻辑使用 TRUE 和 FALSE 值，在数字电路中用 1 和 0 表示。三种基本逻辑门是：AND（仅当两个输入均为 1 时输出 1）、OR（至少一个输入为 1 时输出 1）和 NOT（单输入门，信号取反：1 变 0，0 变 1）。
A truth table lists every possible combination of inputs and the resulting output of a logic circuit. For a two‑input AND gate, the truth table is: 0,0 → 0; 0,1 → 0; 1,0 → 0; 1,1 → 1. More complex circuits can be built by combining gates — for example a NAND gate is an AND followed by a NOT, giving the inverse output of AND.
真值表列出所有可能的输入组合及其对应的逻辑电路输出。对于两输入 AND 门，真值表为：0,0 → 0；0,1 → 0；1,0 → 0；1,1 → 1。通过组合门可以构建更复杂的电路——例如 NAND 门是与门后接非门，输出与 AND 相反。
Logical expressions can be simplified using Boolean algebra rules such as De Morgan’s laws: NOT(A AND B) = NOT A OR NOT B; NOT(A OR B) = NOT A AND NOT B. In programming, logical operators && (AND), || (OR) and ! (NOT) control flow in compound conditions.
可以使用布尔代数规则简化逻辑表达式，如德·摩根定律：NOT(A AND B) = NOT A OR NOT B；NOT(A OR B) = NOT A AND NOT B。在编程中，逻辑运算符 &&（AND）、||（OR）和 !（NOT）控制复合条件的流程。
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