What is Regular Set in TOC

Q. What is Regular Set in TOC ?

Ans. Regular sets are set which are accepted by FA (finite automata).
For example:
L = {ε, 11, 1111, 111111, 11111111…}

Here L is language set of even number of 1’s.
Finite automata for above language L is,
The give set L is regular set because we can represent it using finite automta.