isr.co.ro : glossary Byte (B) A group of 8 bits, particularly one used to represent a single character or unit of program code. These days, file and memory sizes are more likely to be measured in megabytes (millions of bytes). In some more obscure technical contexts, the basic character or instruction element length in a particular system, even if it is smaller or larger than 8 bits. For that reason, many technical publications, as well as many European languages, refer to 8-bit groupings as octets.