String theory is a theoretical framework that suggests that fundamental particles are not point-like but tiny, vibrating strings. It combines quantum mechanics and general relativity to provide a unified description of all known forces and particles. The theory proposes that the vibrational patterns of these strings determine the properties of particles, such as their masses and charges. String theory also requires the existence of extra spatial dimensions beyond our familiar three dimensions. It remains an active area of research, aiming to reconcile quantum mechanics and gravity while offering new insights into the nature of the universe.