An optical waveguide is a structure that directs light waves along a specific path. It typically consists of a core material with a higher refractive index surrounded by a cladding material with a lower refractive index. This design allows light to be confined within the core, enabling efficient transmission over long distances with minimal loss. Optical waveguides are commonly used in various applications, including fiber optics, telecommunications, and integrated optics. They play a crucial role in transmitting data as light signals, making them essential for high-speed internet and advanced communication systems.