8 Bit Byte

Factors behind the ubiquity of the eight bit byte include the popularity of the IBM System/360 architecture, introduced in the 1960s, and the 8-bit microprocessors, introduced in the 1970s. The term octet unambiguously specifies an eight-bit byte (such as in protocol definitions, for example)

Byte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol (RFC 791) refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness.

Otherwise, people have tried with 12 bit byte. Varying byte length in PDP 10. 6, 7 and 9 bits in Univac computers.