What is Byte?

Legal Definition
The byte (/ˈbt/) is a unit of digital information that most commonly consists of eight bits. Historically, the byte (symbol B) 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. The size of the byte has historically been hardware dependent and no definitive standards existed that mandated the size. The de facto standard of eight bits is a convenient power of two permitting the values 0 through 255 for one byte. The international standard IEC 80000-13 codified this common meaning. Many types of applications use information representable in eight or fewer bits and processor designers optimize for this common usage. The popularity of major commercial computing architectures has aided in the ubiquitous acceptance of the 8-bit size.
-- Wikipedia
Legal Definition
A sequence of 8 bits (enough to represent one character of alphanumeric data) processed as a single unit of information.