CMOS is much more than a little chip in your PC. It is a digital logic family considered to be a big improvement over previous logic families such as TTL, RTL, and ECL.

CMOS works over a very wide power-supply range, uses no power when inputs are stable (not changing), and very little otherwise.

Since CMOS is relatively tolerant of system noise (and is itself almost noiseless), is inexpensive and is available from dozens of manufacturers, it is a good choice for digital logic design both in industry and for the hobbyist.