UDP
UDP (User Datagram Protocol) is a what they call a send and pray protocol. You throw data onto the network and have no guarantee if it reaches its destination or even when. Because of this, it is extremely fast, efficient, but also unreliable.
Next to TCP, it is one of the primary basic Internet Protocols that every major OS supports.
Raw UDP cannot normally be used for streaming. RTP is used on top of UDP to provide proper data timestamps and ordering. RTP/UDP is extensively used for streaming live audio/video. In this case it is not important that you receive all data, as long as you receive some data continuously and fast.
Although VLC supports this protocol for streaming, not all audio and video codecs can be used.
See the Streaming features list for further details.
