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.

HEIC is a file extension that Apple uses for the HEIF image format, which are usually coded by HEVC codec (High Efficiency Video Compression). This format is great for Live Photos because it can contain an image sequence. The best part about it is that you can store twice as many pictures in the HEIC format as in JPEG in the same size and quality because it uses the next-generation file compression.