Heading

A heading gives your document its structure: chapters, sections, subsections. LaTeX numbers them, and the table of contents is built from them.

Levels

Select a heading and choose its level in the right column.

A new heading is an H2. Change the level at any time; the text is kept.

Chapters

A chapter starts a new page and prints its number on a line of its own ("Chapter 1", or "Chapitre 1" in a French document) above its title.

A chapter also restarts the numbering of the sections, figures, tables, equations and theorems that follow, and prefixes them with its number: Figure 2.1, equation (2.3). See Numbering and references.

A document does not need chapters. Without any, sections are numbered 1, 2, 3 and nothing is prefixed.

Numbered or plain

Plain removes the number. A plain heading:

• prints no number;
• does not count: the next numbered heading continues from the last numbered one;
• is left out of the table of contents;
• cannot be the target of a cross-reference;
• if it is a chapter, does not restart the numbering of what follows.

It is the right choice for an introduction, a conclusion, acknowledgements or an appendix title you do not want numbered.

What a heading can contain

• Bold, italic, underline, strikethrough.
• Formulas — Ctrl+M, or type $…$.
• Cross-references and citations.

A heading is one line of text. Enter at the end of a heading starts a paragraph below it.

What it cannot do

• No footnote in a heading. The footnote button is not offered there.
• No colour in a heading. The colour button is not offered there either: a coloured title would colour its line of the table of contents.
• No chapter inside a column. A chapter starts a new page, which a column cannot do: a chapter placed in a column is set as a section, and becomes a chapter again when you move it out.
• No heading inside a theorem.
• No custom numbering (letters, Roman numerals) and no appendix mode.
• H3 is not numbered in a document that has chapters, whatever the Numbered/Plain setting: subsections already read 2.1.1 there, and a fourth level (2.1.1.1) is not printed. One numbered chapter anywhere in the document is enough. Without chapters, H3 is numbered 1.1.1 and can be referenced.

What it prints

\chapter{Groups}\label{blk-…}
\section{Definitions}\label{blk-…}
\subsection*{A plain subsection}

The \label is what cross-references point at. A plain heading uses the starred command and has no label.