Molecular Orbital Theory (MOT) is a concept in chemistry that explains how molecules form and behave by analyzing the combination of atomic orbitals to create molecular orbitals. Unlike theories that assign electrons to individual bonds between atoms, MOT treats electrons as moving in molecular orbitals that extend over the entire molecule. These molecular orbitals are formed by linear combinations of atomic orbitals from the component atoms. MOT helps understand molecular structure and bonding by describing the quantum mechanical behavior of electrons. It explains properties more accurately for complex molecules, including those with multiple identical bonds, resonance, or delocalized electrons, which simpler theories like Valence Bond Theory cannot fully address. The theory uses principles such as the Pauli exclusion principle, the Aufbau principle, and Hund’s rule to describe how electrons fill these molecular orbitals. Bonding molecular orbitals stabilize a molecule by concentrating electrons between nuclei, while antibonding molecular orbitals, formed by out-of-phase combinations of atomic orbitals, make a molecule less stable. In summary, MOT provides a quantum mechanical framework to predict electron distribution, molecular properties, magnetism, and bond order in molecules.