PNG [pronounced "ping"? is the Acronym for Portable Network Graphics, a new, losslessly compressed bitmapped graphics format. It is approved by the World Wide Web consortium as the successor of the GIF format. The latter depends on a compression algorithm called LZW patented by Unisys. In contrast, PNG relies on the patent free LZSS for compression and is completely unencumbered with licensing fees. The most recent versions of NetscapeNavigator and Microsoft InternetExplorer now support PNG, although the latter doesn't support alpha channels.

Rumours have it that the IE engine is too old and out of date to support transparency without lots of hideous hacks. Amusingly, while Microsoft can't make these hideous hacks, we can.