AMS-LaTeX is a collection of LaTeX document classes and packages developed for the American Mathematical Society (AMS). Its additions to LaTeX include the typesetting of multi-line and other mathematical statements, document classes, and fonts containing numerous mathematical symbols.

It has largely superseded the plain TeX macro package AMS-TeX. AMS-TeX was originally written by Michael Spivak, and was used by the AMS from 1983 to 1985.

MathJax supports AMS-LaTeX through extensions.

The following code of the LaTeX2e produces the AMS-LaTeX logo:

The package has a suite of facilities to format multi-line equations. For example, the following code,

causes the equals signs in the two lines to be aligned with one another, like this:

${\displaystyle {\begin{aligned}y&=(x+1)^{2}\\&=x^{2}+2x+1\end{aligned}}}$

AMS-LaTeX also includes many flexible commands for formatting and numbering theorems, lemmas, etc. For example, one may use the environment theorem

to generate

Theorem (Pythagoras) Suppose ${\displaystyle a\leq b\leq c}$ are the side-lengths of a right triangle.
Then ${\displaystyle a^{2}+b^{2}=c^{2}}$.
Proof. . . □