\chapter ¶Synopsis, one of:
\chapter{title}
\chapter*{title}
\chapter[toc-title]{title}
Start a chapter. The standard LaTeX classes book and
report have this command but article does not.
This produces a chapter.
\chapter{Loomings}
Call me Ishmael.
Some years ago---never mind how long precisely---having little or no
money in my purse, and nothing particular to interest me on shore, I
thought I would sail about a little and see the watery part of
the world.
The LaTeX default starts each chapter on a fresh page, an
odd-numbered page if the document is two-sided. It produces a chapter
number such as ‘Chapter 1’ in large boldface type (the size is
\huge). It then puts title on a fresh line, in boldface
type that is still larger (size \Huge). It also increments the
chapter counter, adds an entry to the table of contents
(see Table of contents, list of figures, list of tables), and sets the running header
information (see Page styles).
The * form shows title on a fresh line, in boldface.
But it does not show the chapter number, does not increment the
chapter counter, produces no table of contents entry, and does
not affect the running header. (If you use the page style
headings in a two-sided document then the header will be from the
prior chapter.) This example illustrates.
\chapter*{Preamble}
The optional argument toc-title will appear as the chapter title in the table of contents (see Table of contents, list of figures, list of tables) and in running headers (see Page styles). If it is not present then title will be there. This shows the full name in the chapter title,
\chapter[Weyl]{Hermann Klaus Hugo (Peter) Weyl (1885--1955)}
but only ‘Weyl’ on the contents page. This puts a line break in the title but that doesn’t work well with running headers so it omits the break in the contents
\chapter[Given it all; my story]{Given it all\\ my story}
For determining which sectional units are numbered and which appear in the table of contents, the level number of a chapter is 0 (see Sectioning/secnumdepth and see Sectioning/tocdepth).
The paragraph that follows the chapter title is not indented, as is a
standard typographical practice. To get an indent use the package
indentfirst.
You can change what is shown for the chapter number. To change it to
something like ‘Lecture 1’, put in the preamble either
\renewcommand{\chaptername}{Lecture} or this
(see \makeatletter & \makeatother).
\makeatletter
\renewcommand{\@chapapp}{Lecture}
\makeatother
To make this change because of the primary language for
the document, see the package babel.
In a two-sided document LaTeX puts a chapter on odd-numbered page, if
necessary leaving an even-numbered page that is blank except for any
running headers. To make that page completely blank,
see \clearpage & \cleardoublepage.
To change the behavior of the \chapter command, you can copy its
definition from the LaTeX format file and make adjustments. But
there are also many packages on CTAN that address this. One is
titlesec. See its documentation, but the example below gives a
sense of what it can do.
\usepackage{titlesec} % in preamble
\titleformat{\chapter}
{\Huge\bfseries} % format of title
{} % label, such as 1.2 for a subsection
{0pt} % length of separation between label and title
{} % before-code hook
This omits the chapter number ‘Chapter 1’ from the page but unlike
\chapter* it keeps the chapter in the table of contents and the
running headers.