Quantum particles are the smallest building blocks of matter and energy, existing at the quantum level. They include particles like electrons, protons, and photons, which exhibit unique behaviors that differ from classical physics. For example, they can exist in multiple states at once, a phenomenon known as superposition, and can be entangled, meaning the state of one particle can instantly affect another, regardless of distance. These particles are described by quantum mechanics, a branch of physics that explains their behavior and interactions. Quantum particles are fundamental to understanding various phenomena, including atomic structure, chemical reactions, and the principles behind technologies like quantum computing and semiconductors.