I revisit Youngpup.net looking for some mega cool use of Styles and I came across some interesting articles on PNG ::: http://www.youngpup.net/?request=/snippets/sleight.xml
PNG stands for Portable Network Graphics and is an extensible file format for lossless, portable, well-compressed raster images. PNG is a patents free replacement to GIF. It has an optional alpha channel for transparency and its sample depths range from 1 to 16 bits per component (up to 48bit images for RGB, or 64bit for RGBA).
On a more historical point, PNG began in New Year’s Day 1995 when Unisys and CompuServe suddenly announced that programs implementing GIF would require royalties, because of Unisys’ patent on the LZW compression method used in GIF.
::: http://www.youngpup.net for a historical walkthrough of the PNG format visit Greg Roelofs The Story of PNG.