Linear versus digital

A linear IC is used to process analog signals such as music, voices, and radio transmissions. The term linear comes from the fact that, generally the amplification factor is constant as input amplitude varies. That is, output signal strength is a linear function of input signal strength.

A digital IC, sometimes called as digital-logic IC, operates by using just 2 states, called as high and low. These are called logic 1 and logic 0, respectively. Digital ICs consist of many logic gates which perform  operations  in binary algebra.