A system with a base-2 is a binary system. The binary numeral system allows only two states and is represented by the numbers 0 and 1.
Just like the numbers in the Decimal system use the power of 10 in binary we use the powers of 2
1, 2, 4, 8, 16, 32, 64, 128 …
10 in different numbering systems
Decimal = 10
Binary = 0b1010
octal = 0o12
Hexadecimal = 0xA (or 0xa)