Bitmap:
It is most commonly used
File extension is .BMP
Paint accessory in windows xp creates these types of pictures.

GIF:
Graphical Interchange Format widely used in internet because it creates very thin files.
This format supports only 256 colors and its file extension is .GIF

JPEG:
Joint Photographic Experts Group format files can be heavily compressed to obtain very thin files
It supports many colors and its extension is .JPEG

PNG:
Portable Network Graphics format files are very thin, not widely supported. File extension is .PNG.

TIFF:
Tagged Image Format was quite popular in the past
its extensions is .TTF

ICO:
The icon files are stored in the file extension .ICO
Icons are small pictures and these files are generally used by system programmers.

WMP:
Windows meta format, the file extension for which is .WMF

EMF:
Enhanced Meta File(. EMF) format is a modified version of WMF files.

that's it.

Thankyou,

Rajkumar