.TEX

Introduction

A .tex file is the source of a document typeset by TeX, the typesetting system Donald Knuth wrote from 1978, or, far more often today, by LaTeX, the set of macros Leslie Lamport built on top of it in the 1980s. The author writes plain text with commands for structure and maths, and a TeX engine turns it into a finished PDF. It is the standard way to write papers in mathematics, physics and computer science, and is used for many books and theses.

Structure

A LaTeX file is plain text. Commands start with a backslash, such as \section{Results} or \emph{word}, with required arguments in braces and optional ones in square brackets. The preamble chooses a document class with \documentclass and loads packages with \usepackage; the text itself sits between \begin{document} and \end{document}. Maths is written between dollar signs or in environments such as equation, and % starts a comment. Larger documents are split into several .tex files joined with \input or \include, with references in a separate .bib file.

\documentclass{article}
\usepackage{amsmath}
\title{A Short Note}
\begin{document}
\maketitle
\section{Introduction}
Euler's identity is $e^{i\pi} + 1 = 0$.
\end{document}

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