What has Albert Einstein invent?

Answer 1

E=mc2 which is the main and important one for everything now.

+++

He did not "invent" anything. He was a theoretical physicist who studied the relationships between mass, energy etc., with a particularly original insight that led to some of the most important discoveries in science. Yes, that equation is always being quoted but he did not "invent" it, and an equation like that on its own it is no more than a bit of basic algebra: you need to understand its context fully to understand its significance.