GIF is the original format with transparency support for the Web. The problem with GIF is that it reduces the color palette to no more than 256 colors, causing color shifts, posterization, and distortion in high color images such as photographs. Another downside to GIF is that it only supports 1-bit transparency, meaning you can't have areas of partial transparency. Each pixel is either completely transparent or not, so you cannot do things like smooth drop shadows that fade away gradually.
PNG is a newer format developed to overcome many of the limitations of GIF. It supports high color and partial transparency using alpha channels. Although PNG has been around for a while now, the biggest problem with it is that many people are still using older browsers that do not support PNG, and even some modern browsers do not support all the features of PNG. Case in point, Microsoft Internet Explorer 6, the most widely used browser today, does not support alpha transparency of PNG images.
De asta vroiam sa folosesc neaparat png-uri.

Oricum daca png nu se poate, asta e.. merg pe gif.


Heil Microsoft!