Voltage Comparator.

A comparator is an example of a ___________.
A __________ is an electronic circuit which compares the two inputs that are applied to it and produces an output.
_______ is an op-amp based comparator for which a reference voltage is applied to its non-inverting terminal and the input voltage is applied to its inverting terminal.
How the op-amp comparator should be choosen to get higher speed of operation?
Identify the op-amp application which doesn't have feedback.