is a format used in the MobiPocket Reader software on desktop and mobile platforms. Books in this format can have .prc and .mobi file extensions. MOBI was originally based on the PalmDOC format; adding HTML tags made it possible to create a high-compression version which compresses data to a high degree. There are a number of formatting restrictions – the text cannot be indented, and inserted tables and images cannot be formatted.
JPG extension was assigned to the image files. Many photos and web graphics are saved in JPG. In order to compress many bitmaps are saved in .jpg, that makes it easier to transfer and download these files on the Internet. JPG format based on the 24-bit color palette, the higher the level of compression applied to create the file JPG, the greater the decompression effect on image quality.