PNG 
Portable Network Graphics 
A graphics file format that combines many of the benefits of the GIF and JPEG graphics file formats. PNGs also allows or many features that GIFs don't, including 254 levels of transparency (GIFs support only 1), more control over image brightness, and support for more than 256 colors. PNGs also support progressive rendering, as interlaced GIFs do, and tend to compress better than GIFs (when the compressed file is decompressed for viewing, it retains all of the graphics information of the original).