📚 Software: System Software, Application Software and Programming Concepts | 软件：系统软件、应用软件与编程概念
Software is often called the invisible part of a computer system. While hardware provides the physical machinery, software supplies the instructions that make the machine useful. This revision guide explains the types of software, how software is created and translated, and why updates and security matter.
软件通常被称为计算机系统中看不见的部分。硬件提供物理机器，而软件提供使机器有用的指令。本复习指南解释软件的类型、软件是如何创建和翻译的，以及为什么更新和安全很重要。
1. What is Software? | 什么是软件？
Software is the collection of programs, data and instructions that tell a computer how to work. Unlike hardware, you cannot touch software physically; it is stored as binary code on storage devices and loaded into memory when needed.
软件是告诉计算机如何工作的程序、数据和指令的集合。与硬件不同，软件无法被物理触摸；它以二进制代码的形式存储在存储设备上，并在需要时加载到内存中。
Software can be divided into two main groups: system software, which manages the computer itself, and application software, which helps users perform tasks such as writing, calculating or browsing.
软件主要分为两大类：系统软件，用于管理计算机本身；应用软件，用于帮助用户执行写作、计算或浏览等任务。
2. Hardware vs Software | 硬件与软件的区别
Hardware refers to the physical parts of a computer, such as the CPU, RAM, keyboard and monitor. Software is the non-physical set of instructions that runs on hardware and gives the hardware a purpose.
硬件指计算机的物理部件，例如 CPU、内存、键盘和显示器。软件是运行在硬件上并赋予硬件用途的非物理指令集合。
A simple comparison is that hardware is like a car body and engine, while software is like the driver who decides how the car moves. Hardware cannot function without software, and software needs hardware to execute instructions.
一个简单的类比是，硬件就像汽车车身和发动机，而软件就像决定汽车如何行驶的驾驶员。硬件没有软件无法工作，软件也需要硬件来执行指令。
3. System Software and the Operating System | 系统软件与操作系统
System software manages and controls the computer hardware so that application software can run. The operating system is the most important system software. It handles memory management, processor scheduling, file management, input/output control and the user interface.
系统软件管理和控制计算机硬件，使应用软件能够运行。操作系统是最重要的系统软件。它负责内存管理、处理器调度、文件管理、输入输出控制和用户界面。
Common operating systems include Windows, macOS, Linux, Android and iOS. Without an operating system, users and application programs would have to communicate directly with hardware, which is very difficult.
常见的操作系统包括 Windows、macOS、Linux、Android 和 iOS。如果没有操作系统，用户和应用程序就必须直接与硬件通信，这是非常困难的。
4. Utility Software | 实用程序软件
Utility software is a type of system software designed to help maintain, analyse or protect the computer. Examples include antivirus programs, disk defragmenters, backup tools, file compression utilities and encryption software.
实用程序软件是一种系统软件，旨在帮助维护、分析或保护计算机。示例包括防病毒程序、磁盘碎片整理工具、备份工具、文件压缩实用程序和加密软件。
Utilities usually run in the background or are launched when the user needs a specific maintenance task. For example, an antivirus utility continuously scans files, while a backup utility may run on a schedule.
实用程序通常在后台运行，或在用户需要执行特定维护任务时启动。例如，防病毒实用程序会持续扫描文件，而备份实用程序可能按计划运行。
5. Application Software | 应用软件
Application software allows users to perform specific tasks. It can be general-purpose, such as word processors, spreadsheets, presentation software and web browsers, or special-purpose, such as accounting packages, image editors, video games and school management systems.
应用软件让用户执行特定任务。它可以是通用的，例如文字处理软件、电子表格、演示软件和网页浏览器；也可以是专用的，例如会计软件包、图像编辑器、视频游戏和学校管理系统。
Application software relies on the operating system to provide services such as saving files, printing documents and connecting to the internet. For instance, a photo editor asks the OS to read a file from disk and display it on screen.
应用软件依赖操作系统提供保存文件、打印文档和连接互联网等服务。例如，照片编辑器要求操作系统从磁盘读取文件并在屏幕上显示。
6. Open Source vs Proprietary Software | 开源软件与专有软件
Open source software allows users to view, modify and share its source code, usually free of charge. Examples include Linux, LibreOffice and GIMP. Proprietary software keeps its source code closed and requires a paid license or agreement; examples include Microsoft Office and Adobe Photoshop.
开源软件允许用户查看、修改和分享其源代码，通常免费。例子包括 Linux、LibreOffice 和 GIMP。专有软件将其源代码封闭，并要求付费许可或协议；例子包括 Microsoft Office 和 Adobe Photoshop。
Open source offers flexibility and community support, while proprietary software often provides dedicated customer support and regular official updates. The choice depends on user needs, budget and technical ability.
开源软件提供灵活性和社区支持，而专有软件通常提供专门的客户支持和定期官方更新。选择取决于用户需求、预算和技术能力。
7. Programming Languages and Translators | 编程语言与翻译器
Software is written in programming languages. High-level languages such as Python, Java and C++ are easier for humans to read and write because they use English-like words and mathematical symbols.
软件是用编程语言编写的。Python、Java 和 C++ 等高级语言更容易被人类阅读和编写，因为它们使用类似英语的单词和数学符号。
Low-level languages include machine code, which is binary, and assembly language, which uses short mnemonics like ADD or MOV. Since a computer only understands binary machine code, programs written in high-level or assembly language must be translated before execution.
低级语言包括二进制机器码和使用 ADD 或 MOV 等简短助记符的汇编语言。由于计算机只能理解二进制机器码，用高级语言或汇编语言编写的程序必须在执行前翻译。
Translators include compilers, interpreters and assemblers.
翻译器包括编译器、解释器和汇编器。
8. Compilers, Interpreters and Assemblers | 编译器、解释器与汇编器
A compiler translates the entire high-level source code into machine code before execution, producing an executable file. An interpreter translates and executes the source code line by line, without producing a separate executable. An assembler converts assembly language into machine code.
编译器在执行前将整个高级源代码翻译为机器码，并生成可执行文件。解释器逐行翻译并执行源代码，不生成单独的可执行文件。汇编器将汇编语言转换为机器码。
Compiled programs usually run faster after translation because the machine code is ready, while interpreted programs are easier to debug and test because errors can be found line by line.
编译后的程序在翻译后通常运行更快，因为机器码已经准备好；而解释执行的程序更容易调试和测试，因为可以逐行发现错误。
9. The Fetch-Decode-Execute Cycle and Software Instructions | 取指-译码-执行周期与软件指令
At the machine level, software is a set of binary instructions stored in memory. The CPU processes each instruction by repeatedly performing the fetch-decode-execute cycle: it fetches an instruction from memory, decodes what operation is required, and executes it by using the appropriate hardware component.
在机器层面，软件是一组存储在内存中的二进制指令。CPU 通过反复执行取指-译码-执行周期来处理每条指令：它从内存中取出指令，译码需要执行的操作，并使用适当的硬件组件执行该操作。
This cycle shows how software instructions control hardware at the lowest level. For example, when a user saves a file, a long sequence of binary instructions directs the CPU, memory and storage device to complete the task.
这个周期展示了软件指令如何在最低层面控制硬件。例如，当用户保存文件时，一系列二进制指令会指挥 CPU、内存和存储设备完成任务。
10. Firmware and Embedded Software | 固件与嵌入式软件
Firmware is a special type of software stored permanently on
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