In real-time scenarios such as video conferencing, online gaming, and live streaming, UDP’s speed and efficiency make it irreplaceable. For applications demanding ultimate efficiency and low latency, the User Datagram Protocol (UDP) offers a minimalist alternative. This chapter explores UDP as a lightweight, connectionless transport layer protocol, detailing its core characteristics and minimal header structure. This chapter delves into UDP’s strengths and weaknesses (fast but unreliable) and how application-layer protocols like QUIC and RTP can optimize it. Finally, a hands-on experiment implementing UDP client–server communication and exercises comparing TCP and UDP helps students apply theoretical knowledge to real-world scenarios.