Who or what is an Antagonist and a Protagonist?

Do societies define hero, heroins & villains, do hero and villains guide societies or is there an absolute hero and a villain?

India is a land where antagonist and protagonist are worshipped equally. Whats your process of defining them?

What could be parameters to gauge a character since a very subjective thing? It’s a question to become a better audience?

If there is a gun in the first act then it should fire in the third. How true it is and how have you used it in your plays?