LaTeX offers a lot of functions by default, but in some situations it can become in handy to use so called *packages.* To import a package in LaTeX, you simply add the *\usepackage* directive to the *preamble* of your document:

\documentclass{article} \usepackage{PACKAGENAME} \begin{document} ...

## Install a package

When using Linux or Mac, most packages will already be installed by default and it is usually not necessary to install them. In case of Ubuntu installing *texlive-full *from the package manager would provide all packages available. The MiKTeX bundle in Windows, will download the package if you include it to your document.

## Purpose of packages

There are countless packages, all for different purposes in my tutorials I will explain some of the most useful. To typeset math, LaTeX offers (among others) an *environment *called *equation. *Everything inside this environment will be printed in *math mode*, a special typesetting environment for math. LaTeX also takes care of equation numbers for us:

\documentclass{article} \begin{document} \begin{equation} f(x) = x^2 \end{equation} \end{document}

This will result in the following output: $f(x) = x^2$ (1)

## Using / Including a package

The automatic numbering is a useful feature, but sometimes it's necessary to remove them for auxiliary calculations. LaTeX doesn't allow this by default, now we want to include a package that does:

\documentclass{article} \usepackage{amsmath} \begin{document} \begin{equation*} f(x) = x^2 \end{equation*}

Now we get the same output as before, only the equation number is removed: $f(x) = x^2$

## Summary

*Packages*add new functions to LaTeX- All
*packages*must be included in the*preamble* - Packages add features such as support for pictures, links and bibliography

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