How TCP is different from UDP

Unlike TCP, UDP is connectionless and provides no reliability, no windowing and no function to ensure data is received in the same order as it was transmitted. However, UDP provides some functionalities as supported by UDP such as data transfer, multiplexing and has fewer bytes of overhead in the data. This fewer bytes in the overhead makes UDP protocol need less time in processing the packet and need less memory. Also, absence of acknowledgement field makes it faster as it need not to wait on ACK or need not to have hold on data in memory until they are ACKed.