> For the complete documentation index, see [llms.txt](https://ayakaleaf-pro.ayaka.space/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ayakaleaf-pro.ayaka.space/latex/zh-cn/lei-wen-jian/01-understanding-packages-and-class-files.md).

# 理解宏包和类文件

LaTeX 文档中的默认格式由……决定 **类** 该文档所使用的。这种默认外观可以通过……来更改，并且可以通过……添加更多功能。 **宏包**。类文件名具有 **.cls** 扩展名，宏包文件名具有 **.sty** 扩展名。

## 类与宏包之间的区别

有时，在决定是编写宏包还是类时，很难做出选择。基本规则是：如果你的文件包含控制某种特殊类型文档的逻辑结构外观的命令，那么它就是一个类。否则，如果你的文件添加的是与文档类型无关的功能，也就是说，可用于书籍、报告、文章等；那么它就是一个宏包。

例如，如果某家公司需要带有品牌标识的报告，这些报告使用一种特殊字体，并且在页脚中包含公司的徽标；那么你需要一个新的类。

如果公司需要一个新命令，使在文档中突出显示重要句子更容易，那么在这种情况下，一个新的宏包就能满足需求。

## 进一步阅读

更多信息请参见

* [编写你自己的宏包](/latex/zh-cn/lei-wen-jian/03-writing-your-own-package.md)
* [编写你自己的类](/latex/zh-cn/lei-wen-jian/04-writing-your-own-class.md)
* [面向类和宏包编写者的 LaTeX2ε](http://www.latex-project.org/guides/clsguide.pdf)


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