The Quick List
 
If you just want some quick notes and comments about different file formats here's a quick and dirty list.
.bmp
 "Windows Bitmap" file format
16,777,216 colors per image
No loss in quality
Large size files, no compression
Significant file size reduction with winzip(*.zip)
.gif
 GIF (Graphic Interchange Format)
A maximum of 256 unique colors per image
No loss in quality (for images with 256 colors or less). Images with more than
   256 colors may show a loss in quality when reduced to 256 colors.
Small size files, indexed color compression
Supports transparency
Supports animation
No file size reduction with winzip(*.zip)
.jpg
 JPEG (Joint Photographic Experts Group)
16,777,216 colors per image
Variable quality depending on amount of compression
Very Small size files, quality loss due to compression
No significant file size reduction with winzip(*.zip)
.tif
 TIFF(Tagged Image File Format)
Near unlimited unique colors per Image
No loss in quality
Large size files, multiple compression options available
No significant file size reduction with winzip(*.zip)
Alpha channel supported
Multiple file type available