A bit is the basic unit of almost every modern computer system. The word bit is a contraction of the term binary digit.
A bit is the building block for the numbers, languages, and almost every aspect of computer operation. It is also the smallest "irreducible" unit of information in those computers.
A binary unit can only have two values or logical states, typically the values are 0 and 1. But the values could also be Off and On, False and True or No and Yes.