JPEG (or JPG) : Joint Photographic Group Experts.

It is a format of very widespread display file which authorizes a variable compression of the images being able to go until a factor 150 compared to the original. A strong compression makes it possible to obtain smaller files and to make circulate these images more quickly on Internet... but the more they are compressed, the more they lose in quality.

Format JPEG is compatible with all the navigators, like the GIF, but it is adapted better to the photographs than this one, because it manages 16,7 million colors exactly... (16 777 216), that is to say 24 bits per pixel.

GIF : Graphic Interchanges Format.

It is a compressed format of images of 256 colors maximum, that is to say 8 bits per pixel, exploitable with a PC or Mac. It is used on the Web because of its compactness and its possibilities of transparency.

Animated GIF : format GIF allows the creation of animations based on a sequence of images to which one can apply effects and transformations.

PIXEL : digest of Picture Element. Not elementary of posting.