Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.In computing, an octet is a grouping of eight bits. Octet, with the only exception noted below, always refers to an entity having exactly eight bits. As such, it is often used where the term byte might be ambiguous. For that reason, computer networking standards almost exclusively use octet. It is prominently used in Requests for Comments (RFCs) published by the Internet Engineering Task Force. The earliest example is RFC 635 from 1974. In France, French Canada and Romania, the word octet is commonly used instead of byte (in the 8-bit sense); a megabyte (MB) is called a megaoctet (Mo). Early in its history, in the age of computer science preceding tabletop and desktop microcomputers (the earliest of which almost all used 8-bit data words,) the word byte was not standardized to 8 bits and could indicate a unit of different sizes (all relatively small) in different contexts and for different machines. Hence, while to most people today, byte and octet are synonyms, those working with certain legacy systems need to be careful to avoid ambiguity.