This is a format that applies an 8-bit encoding to images for the purpose of compression and transportation. The format was originally developed for the Utah Raster Toolkit software package for managing bitmaps. The compression algorithm provides a replacement for repeating strings of bytes into pairs, which significantly reduces the file size.

Is based on the XML format. Its main tasks are: precise display on a variety of devices, full preservation of document structure, ability to be transformed into other formats. Unlike other popular e-book formats, fb2 does not specify the appearance options for different devices’ displays. The format employs tools to indicate the different parts of the book – verses, epigraphs, quotations.