LaTeX

LaTeX is a document encoding format optimized for paper-oriented formats with a particular focus on typesetting. Similarly to HTML, LaTeX allows specifying both content and layout properties either in combined or decoupled manner. It is customary, though, to produce clean documents which only contain the semantic structure (chapters, sections, emphasis, etc.), and declare the formatting directives in a separate ‘template’ file.

LaTeX is the de facto document encoding format in academic, scientific, and engineering settings given its built-in support for typesetting mathematical formulae and its friendliness toward DocOps workflows. LaTeX embraces the tenet of composability and automated content generation, encouraging the organization of complex documents by composing and reusing document files, as well as the programmatic generation of text and images using tools macros and tools such as TikZ, respectively.

LaTeX is well-maintained and its specification thoroughly documented.

Example

\documentclass{article} 
\begin{document}
\section{This is a level 1 heading}\label{this-is-a-level-1-heading}

\subsection{This is a level 2 heading}\label{this-is-a-level-2-heading}

This is text in \textbf{bold} and \emph{italics}, and this is an
external link to \href{https://docops.guide}{DocOps}. Now, some bullet
points:

\begin{itemize}
\item
  Bullet point 1
\item
  Bullet point 2
\item
  Bullet point 3
\end{itemize}
\end{document}

Note that the above example assumes an article as opposed to a book class, and that some extra directives are normally expected to specify the title, author, and date, after \begin{document}. For example:

\title{A Small LaTeX Article}
\author{John Doe}
\date{\today} 
\maketitle