The Pauli Exclusion Principle is a fundamental principle in quantum mechanics that states that no two identical fermions can occupy the same quantum state simultaneously. There are several synonyms for the Pauli Exclusion Principle, including the Pauli Exclusion Rule, Pauli's Principle, Pauli's Exclusion Principle, and the Pauli Exclusion Principle of Quantum Mechanics. These terms are all used to describe the same concept, which is the foundation for many of the properties of matter at a microscopic scale. The Pauli Exclusion Principle impacts the behavior of electrons in atoms, leading to the unique properties of the periodic table and the behavior of materials in the world around us.