Adjective describing a variable that can have only two possible values. The values are usually 0 and 1. The binary system is a system of counting using just these digits. In this system the decimal numbers 1, 2, 3, 4,…, 8,…, 16,…, 32,…, become 1, 10, 11, 100,…, 1 000,…, 10 000,…, 100 000,….