UDP is a connectionless protocol that transmits data in units called datagrams (similar to packets). Unlike TCP, which provides guarantees for data delivery, UDP offers reliability only at the datagram level. This means datagrams may arrive out of order, be lost entirely, or reach their destination without confirmation. Additionally, UDP does not implement congestion control, making it generally more efficient for certain applications.
One of the key features of UDP is its ability to broadcast datagrams to all devices on a subnet. This capability is particularly useful in scenarios like DHCP, where the client has not yet received an IP address, thereby preventing the establishment of a TCP stream without an assigned address.
While UDP is less reliable than TCP, it excels in real-time applications such as VoIP video chats (e.g., Zoom/Skype), streaming (Twitch), and real-time multiplayer games due to its lower latency.
Use UDP over TCP when:
- You need the lowest latency.
- Late data is worse than loss of data
- You want to implement your own error correction