All data is stored magnetically with polarities of 0 and 1, which are read as binary digits.
A bit (binary digit) is the smallest unit of data that a computer can process and store.
A bit is always in one of two physical states, similar to an on/off light switch. The state is represented by a single binary value, usually a 0 or 1.
In computer applications, where binary numbers are represented by only two symbols or digits, i.e. 0 (zero) and 1(one).
The binary numbers here are expressed in the base-2 numeral system. For example, (101)2 is a binary number. Each digit in this system is said to be a bit.
Learn more about binary digits here: