The name of Albert Einstein is usually associated by the public with the theory of relativity. There are not many who know he played such a manifold role in the development of physics and scientific thought in the 20th century. In order to understand the revolutionary character of Einstein's works, this lecture will give a short presentation on the status quo in physics at the end of the 19th century, and reviews the areas where the results of Einstein opened up new paths for physics. His discoveries were decisive in the initiation and development of quantum theory and have their impact even today, not only on the scientific way of thinking, but also in the field of applications. The vision created by quantum theory on microparticles, namely their dual- and particle-wave character, is based on the discovery by Einstein of the particle of light, the photon. It only turned out twenty years later, when quantum mechanics was created, that this applies to microparticles in general as well. It is on the basis of his works that the discharge of nuclear power and the physical theory of lasers are based, and the general theory of relativity provides the basis for modern research in physics and cosmology about the structure and development of the Universe.