首先，以下面示例开始。
\documentclass[12pt]{article}
% \usepackage{indentfirst}
\begin{document}
\section{Paragraph Indentation 1}
LaTeX is a high-quality typesetting system; it includes features
designed for the production of technical and scientific documentation.
LaTeX is the de facto standard for the communication and publication of
scientific documents. LaTeX is available as free software.
LaTeX is a high-quality typesetting system.
LaTeX is a high-quality typesetting system.
\section{Paragraph Indention 2}
\setlength\parindent{1em}
LaTeX is a high-quality typesetting system; it includes features
designed for the production of technical and scientific documentation.
LaTeX is the de facto standard for the communication and publication of
scientific documents. LaTeX is available as free software.
\setlength\parindent{5em}
\noindent LaTeX is a high-quality typesetting system.
LaTeX is a high-quality typesetting system.
LaTeX is a high-quality typesetting system.
\setlength\parindent{3em}
LaTeX is a high-quality typesetting system.
\setlength\parindent{0em}
LaTeX is a high-quality typesetting system.
\end{document}
缩进：在文章的段落中，为了让段落更加突出，将段落的首行向右移动，留出的一块空白。
根据上面的示例，我们可以有以下几个结论：
- 除每章节的第一段，所有的段落默认都有缩进；
- 通过
\setlength\parindent{5em}可以设置段落的缩进距离； - 以上的命令会影响其后所有的段落；
- 若要第一行也要缩进，可以使用
\usepackage{indentfirst}。
