Integrated Circuit (IC) is an electronic assembly built in such a way that all the components in the circuit are fabricated on a single container called the chips.

(1) When the input and output relationship of a circuit is linear, Linear IC's are used. Input and output can take places on a continuous range of values. Examples are operational amplifiers, power amplifiers, microwave amplifiers, and multipliers, etc.
Digital IC's : A circuit configuration or approach used to produce a type of Digital Integrated Circuits.
Different logic functions when fabricated in the form of an IC with the same approach, or in other words belonging to the same logic family, will have identical electrical characteristics.