base 2 is a positional numeral system with two as its base. It uses 2 different digits for representing numbers. The digits for base 2 could be 0, and 1.
ternary (base 3)
The ternary numeral system (also called base-3) has three as its base. Analogous to a bit, a ternary digit is a trit (trinary digit). One trit is equivalent to log23 (about 1.58496) bits of information.