Multiplexing techniques refer to the methods used to combine multiple signals or data streams into a single transmission medium in order to optimize bandwidth usage and efficiency. These techniques are commonly used in telecommunications, networking, and data transmission systems to increase the capacity and speed of communication channels. There are several types of multiplexing techniques, including time division multiplexing (TDM), frequency division multiplexing (FDM), wavelength division multiplexing (WDM), and code division multiple access (CDMA). TDM involves dividing the channel into time slots and assigning each signal a specific slot to transmit data sequentially. FDM involves dividing the channel into different frequency bands, with each signal assigned a separate band for simultaneous transmission. WDM uses different wavelengths of light to transmit multiple signals over a single optical fiber. CDMA allows multiple users to share the same frequency band by encoding each signal with a unique code. Overall, multiplexing techniques play a crucial role in optimizing the use of communication channels and improving the efficiency of data transmission in various systems.