The binary system has a radix of 2.
The radix of a number system is the number of unique digits used in that system. For example, in the decimal system (base 10), the radix is 10, because we use 10 unique digits (0 to 9) to represent numbers.
In the binary system (base 2), the radix is 2, because we only use 2 unique digits: 0 and 1. This means that every number can be represented as a combination of only 0s and 1s in the binary system.