pgf -- A Portable Graphic Format for TeX

PGF is a macro package for creating 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. 

Its usage is similar to pstricks and the standard picture
environment.  PGF works with plain (pdf-)TeX, (pdf-)LaTeX, and
ConTeXt.  Unlike pstricks, it can produce either PostScript or PDF output.

The material in base/ is by the author of the pgf package.

The material in contrib/ is by various authors, not necessarily
associated with the authors of the base material.