What is Logic?

Logic is the science of correct thinking.

A classic definition is new and necessary reasoning. It's new because you didn't know the item before, and necessary because a correctly formulated syllogism has to be true if the bases are true.

This syllogism is a well-known example:

All men are mortal.

Socrates is a man.

Therefore, Socrates is mortal.

We took two axioms and made a new and necessary conclusion.