Code Division Multiplexing (CDM) is a communication technique that allows multiple signals to be transmitted simultaneously over a single channel. Each signal is encoded with a unique code, enabling the receiver to distinguish between them. This method is widely used in mobile phone networks and satellite communications. In CDM, the unique codes are spread across the available bandwidth, allowing for efficient use of the spectrum. This technique enhances the capacity of the communication system and reduces interference, making it a popular choice for modern wireless technologies, including CDMA (Code Division Multiple Access) systems.