Base-8 (also called octal) number system uses eight symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5, 6 and 7.
Definition of Octal Number System: The octal number system is the base-8 number system, and uses the digits 0 to 7. That is to say 10octal represents eight and 100octal represents sixty-four.
In the early phase of modern computer development, 6-bit, 12-bit binary words were vastly used. Octal numbers were ideal for abbreviating those words. In the current times, however, 32-bit, 64-bits and even bigger binary words are used in computers.