CTAN should always be your first port of call when looking for a software update or a feature you want to use. To help prevent overload on the volunteers, please don’t ask the network help resources until you have checked CTAN and the FAQ (§ 3.3.1) first.
The Comprehensive TEX Archive Network (CTAN) is a repository of Web documents and files from HTTP and FTP servers worldwide which contain copies of almost every piece of free software related to TEX and LATEX.
CTAN is based on three main servers, and there are several online indexes available. There are complete TEX and LATEX systems for all platforms, utilities for text and graphics processing, conversion programs into and out of LATEX, printer drivers, extra typefaces, and (possibly the most important) the LATEX packages. The three main servers are:
TEX Users Group: http://www.ctan.org/
UK TEX Users Group: http://www.tex.ac.uk/
Deutschsprachige Anwendervereinigung TEX e.V. (DANTE, the German-speaking TEX Users Group); http://dante.ctan.org/
In addition, there are dozens of mirrors of CTAN around the world, run by ISPs, companies, universities, and other institutions. These automatically update themselves from the three main servers, so for a speedy download from your closest server, you can go to mirrors.ctan.org and it will redirect you to your nearest mirror site.