Quantum physics is the study of matter and energy at its most fundamental level, focusing on the behavior of atoms and subatomic particles. While classical physics—like Newton’s laws—works for the macroscopic world we see, it fails to explain the strange, counterintuitive behaviors of the very small. Core Concepts of the Quantum World
Quantum mechanics is built on a few "mind-bending" pillars that challenge our usual understanding of reality: What Is Quantum Physics? - Caltech Science Exchange Quantum Physics in Minutes