Digital electronics is the branch of electronics based on the combination and switching
of voltages called logic levels. Any quantity in the outside world, such as temperature,
pressure, or voltage, can be symbolized in a digital circuit by a group of logic voltages that,
taken together, represent a binary number.
Each logic level corresponds to a digit in the binary (base 2) number system. The binary
digits, or bits, 0 and 1, are sufficient to write any number, given enough places. The
hexadecimal (base 16) number system is also important in digital systems.