String theory is a theoretical framework in physics that suggests the fundamental building blocks of the universe are not point-like particles, but rather tiny, vibrating strings. These strings can oscillate at different frequencies, and their vibrations determine the properties of the particles they represent, such as mass and charge. The theory aims to unify the four fundamental forces of nature: gravity, electromagnetism, and the strong and weak nuclear forces. By doing so, string theory seeks to provide a comprehensive understanding of the universe, potentially reconciling quantum mechanics and general relativity.