Niels Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory. He is best known for the Bohr model of the atom, which introduced the idea of quantized energy levels for electrons, revolutionizing the way scientists viewed atomic behavior. Bohr's work earned him the Nobel Prize in Physics in 1922, and he played a significant role in the development of quantum mechanics. His philosophical insights into the nature of scientific inquiry and the relationship between classical and quantum physics continue to influence modern physics today.