From the project homepage:
PGF is a TeX macro package for generating graphics. It is platform- and format-independent and works together with the most important TeX backend drivers, including pdftex and dvips. It comes with a user-friedly syntax layer called TikZ.
I have been a happy user of PGF ever since 2006. For certain types of graphics like data structures and geometry, it really makes more sense to “code it” then to “draw it” (interactively). The package is very rich in features, as you can witness just by flipping through the 560 page manual.
560 pages for a package? I know it’s long, but of course you don’t need to learn every single option of every single feature before you can use PGF productively. (Actually, you will use a high-level abstraction layer called TikZ as explained in the manual.) The manual provides several tutorials to help you start.
Lastly, I note that the package is written by fellow Theory researcher Till Tantau. Thank you Till!
P.S. Version 2.0 is in the MiKTeX distribution already. Just do an automatic update.
