Wavelength division multiplexing (WDM) is a technology used in fiber optic communication networks to increase the data carrying capacity of a single optical fiber by transmitting multiple data streams simultaneously at different wavelengths of light. This allows for the transmission of more data over the same physical infrastructure, leading to higher network efficiency and performance. WDM technology divides the available bandwidth of the optical fiber into multiple channels, each assigned to a different wavelength of light. These channels can then carry separate data streams, allowing for multiple communications to occur concurrently without interference. WDM can be implemented in two main forms: coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM), with DWDM being the more advanced and higher capacity option. Overall, WDM technology has revolutionized the capabilities of fiber optic networks by enabling them to handle increasing data demands and support a variety of high-bandwidth applications such as video streaming, cloud computing, and telecommunication services.