PNG graphics seem to be the best-kept secret on the World Wide Web. Netscape's browser has supported it since version 4.04, and Internet Explorer has had it since version 4.0. You can put it right into an IMG tag and have it show up when people visit your site. Adobe Photoshop supports it. Macromedia Flash supports it. QuickTime supports it. But gosh darn it, nobody seems to be using it.

Which is a shame, because it's got all the best features of GIF -- lossless compression, optional transparency -- and JPEG -- millions of colors, patent-free algorithm -- plus a few extras that neither one has, like embeded metadata that search engines can index, automatic gamma correction, and an alpha channel for multiple levels of transparency. It's smaller than a GIF of the same image, and while larger than a JPEG, provides far more detail and no loss of data.

The alpha channel is the biggest obstacle to immediate widespread acceptance of PNG, it seems -- only Netscape 6.1 supports transparency in PNG graphics so far. While this is certainly not the most important feature of the PNG format, it's probably the coolest and consequently the most annoying omission.