The byte is a unit of digital information that has eight bits, which represents a binary number. Before now, the byte was the number of bits used to encode a single character of text in a computer. Therefore it is the smallest addressable unit of memory in so many computer architectures.
One byte is equals to one character of text but in some cases two or more bytes are used. Due to this, an SMS written in Chinese or Cyrillic alphabets has shorter maximum length than one written in the Latin alphabet.