Logic comparators are the workhorse components of modern digital electronics and logic design. The become a key building block in digital logic circuit design and are used in several other key building block logic circuits.

A logic comparator is made by two AND gates, Two inverter/NOT gates, and one NOR gate to be. It takes two inputs and compare the two inputs and produce an output, based on the condition or values of the two inputs.

Two common types of digital comparators exist, an Identity comparator and a Magnitude comparator.  An identity comparator only has one output, whereas a magnitude comparator has three outputs. The magnitude comparator can detect whether the inputs are greater than, less than or equal to each other. 

A similar circuit exists in the analog domain, known as a voltage comparator.  Two input voltages are compared, and the output responds depending on the condition of the two inputs. This allows one to know if the input is great than that of a reference voltage or lower than that of a reference voltage. This concept of comparing two or more inputs is very useful and is used in every single computer, which exists today.