File Extentions

GIF (.gif)
Gifs stand for Graphics Interchange Format. It was introduced into 1987 and is most commonly used for use on the internet as its easily supported and is portable. It uses 8 bits per pixel which allows a single image to reference its own palette of up to 256 different colors chosen from the 24-bit RGB color space. It is also good as it works really well with animated images.
http://en.wikipedia.org/wiki/Graphics_Interchange_Format

TIFF(.tiff)
TIFF stands for Tagged Image File Format. Its used mostly by graphic designers and the publication industry. Its really good for image-manipulation applications as allows you to easily edit and change your image.
http://en.wikipedia.org/wiki/Tagged_Image_File_Format

PNG(.PNG)
PNG stands for Portable Network Graffics. It was created as a replacement for GIF files as it makes the files easier to manipulate and is portable.It supports palette-based images and Grayscale images and full-color non-palette-based images.PNG was approved for this use by the Internet Engineering Steering Group on 14 October 1996.
http://en.wikipedia.org/wiki/Portable_Network_Graphics

RAW(.raw)
RAW stands for Raw Image Format. A raw image file contains minimally processed data from the image sensor of either a digital camera, image scanner, or motion picture film scanner. They are called raw not yet processed and therefore are not ready to be printed or edited. They are quite large files though as it has so much data in one file.
http://en.wikipedia.org/wiki/Raw_image_format

JPEG (.jpeg)
JPEG is used method of lossy compression for digital images and is expescially used with photographers as is small and still allows you manipulate and compress files. The degree of compression can be adjusted, allowing a selectable trade off between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality.
http://en.wikipedia.org/wiki/JPEG

RGB(.rgb)
RGB is a extention created on a Silicon Graphics workstation. Run Length Encoding (RLE) compressed or uncompressed images in grayscale or color, and also supports optional transparency. RGB files can be opened and edited by most image editors, such as Adobe Photoshop and the GIMP. Its good for printing.
http://whatis.techtarget.com/fileformat/RGB-Silicon-Graphics-image-file

CMYK(.cmyk)
A file with the CMYK file extension is a Raw Cyan, Magenta, Yellow, and Black Sample file. like RGB its good for printing images. CMYK allows you see colors on your screen that will be closer to the final printed piece.
https://www.blogger.com/blogger.g?blogID=7548685661884609730#editor/target=post;postID=377568018616649145