In my view, any document with a substantial amount of mathematics should load the packages from AMS-TeX. Hence, most of my document's preambles contain

```
\usepackage{amsmath, amsthm, amssymb, amsfonts}
```

(I could add to that the non-AMS `mathtools`

, etc.). What do each of those packages do? Do I really need to list all of them, or do some of them load others? In particular, does any package load all of them, so that I can simply type

```
\usepackage{ams-everything}
```

shorter than the current list?

## Best Answer

Most of the answer was extracted from the

Introductionsections of the documentation of`amsmath`

and`amsthm`

:`amsmath`

provides miscellaneous enhancements for improving the information structure and printed output of documents containing mathematical formulas. Some of the features provided by this package are:`\DeclareMathOperator`

command (through the auxiliary package`amsopn`

) to define new "operator name" commands analogous to`\sin`

and`\lim`

, including proper side spacing and automatic selection of the correct font style and size (even when used in sub- or superscripts).`eqnarray`

environment to make various kinds of equation arrangements easier to write.`eqnarray`

).`equation`

environment (unlike`eqnarray`

).`tag`

command, an easy way to substitute a variant equation number for a given equation instead of the automatically supplied number.`\text`

command (through the auxiliary package`amstext`

) for typesetting a fragment of text inside a display.`eqref`

command, which provides formatting for equation references`amsthm`

helps to define theorem-like structures; the introduction to the documentation gives a nice concise description of the package:`amssymb`

provides an extended symbol collection. For example, after loading`amssymb`

you have the following additional binary relation symbols:`\barwedge`

,`\boxdot`

,`\boxminus`

,`\boxplus`

,`\boxtimes`

,`\Cap`

,`\Cup`

(and many more), the arrow`\leadsto`

, and some other symbols such as`\Box`

and`\Diamond`

. Another useful feature is the`\mathbb`

command to produce blackboard bold charactersSince

`amssymb`

internally loads`amsfonts`

, it's enough to load the former.As far as I know, there's not a single package loading

`amsmath`

,`amsthm`

, and`amssymb`

so all three of them will have to be loaded when using the standard classes (`book`

,`report`

,`article`

).If one of the document classes of the AMS-collection (

`amsbook`

,`amsart`

) is being used, there's no need to load`amsmath`

, or`amsthm`

;`amssymb`

will have to be explicitly loaded.