Wavelength Division Multiplexing (WDM) is a technology that allows multiple signals to be transmitted simultaneously over a single optical fiber. It achieves this by using different wavelengths, or colors, of light to carry separate data streams. Each wavelength can carry its own information, increasing the overall capacity of the fiber without needing additional physical cables. WDM is commonly used in telecommunications to enhance data transmission efficiency. By combining various wavelengths at the transmitter and separating them at the receiver, WDM enables high-speed internet and communication services. This technology is essential for meeting the growing demand for bandwidth in modern networks.