Question

examples of nonregular languages?

Answer 1

of where?

Answer 2

of any nonempty set A

Answer 3

I know Regular languages are any language \[L \subset A^*\] on A is regular if it can be built up using the elements from A using concatenation, + and the *. examples of regular languages are the binary strings and even the english language itself. but what about nonregular ones? examples of them are what?