GIF is one of the most common raster image formats. Its name is an abbreviation for Graphics Interchange Format File. The developer is the CompuServe organization. A feature of this particular image format is its ability to support the animation function. You can edit animated GIFs in different programs (for example, Easy GIF Animator). Animation is achieved due to the fact that a file of this format carries in itself in a certain sequence several raster images at once. With a depth of up to 256 colors, significant data compression in GIF files is possible without loss of quality.
PDF is short for Portable Document Format, which can be translated from English as “Portable Document Format”. It was developed by Adobe Systems for use by US federal authorities as a tool for storing working documents. This is a universal cross-platform format, which is now standard for electronic documents. It serves to convert text files (including photographs or other images) into electronic documents without any loss. To read PDF files you need special programs - Adobe (Acrobat) Reader, PDF-Viewer and others.