is about commands like `\chapter` or `\section` forming the logical structure of documents. For questions specifically about , or lower-level commands (), add the respective tag to the more general . A popular package is .
LaTeX provides 7 levels of sectioning: `\part`, `\chapter`, `\section`, `\subsection`, `\subsubsection`, `\paragraph`, and `\subparagraph`. `\chapter` is only available in book-type classes (e.g. `book`, `amsbook`, and `report`), and `\part` isn't available in the `letter` class.
Each command also has a starred version, e.g. `\section*{``}`, which produces an unnumbered section. You can also set a short title for headers and the table of contents with `\section[Short Title]{Much Longer Full Title}`.