User Datagram Protocol   The oldest network protocol in existence. Used to send direct messages to hosts over an IP network. Quite an unreliable service as messages may not arrive in the order that they were sent.   Real Time Streaming Protocol   Used to control streaming media servers. Clients of the media server are able to use commands such as play and pause in order to control the playbck of the media files. Some examples of applications that use this protocol are Spotify, Quicktime and Windows Media Player.   Transmission Control Protocol   This is the second of two components of the Internet Protocol Suite. The second of which is Internet Protocol. IP handles low-level transmissions from computer to computer on the internet. Whereas Transmission Control Protocol deals with the higher level transmissions from a programme on one computer to a programme on the other.   Unicast   Unicast is a type of transmission where the client only wishes to send data to one, or a few people. The network connected uses up a lot of computer resources, therefore this method is only useful if sending data to a small amount of people. Unicast-based media servers open up a new stream for each user, therefore it is not suitable for things like online radio.   Multicast Multicast is a type of transmission where the clientwishes to send messages to a group of people. The word multicast is usually used when referring to IP Multicast which is used in streaming media and for use in internet television applications.   IP Multicast   IP Multicast is a technique for communication on a one-to-many basis over an IP infrastructure on a network. This technique is useful as the source only needs to send the packet once. This is because the nodes in the network take care of replicating the data if it needs to be replicated in order to reach multiple receivers.   Peer to Peer   Peer to Peer or P2P is composed of participants who make a portion of their resources available to the other participants in the network. These resources could be disk storage or network bandwidth. Peers in the network can both consume and supply resources rather than just being able to consume or just being able to supply, like in most other forms of transmission. P2P was popularised by the famous file sharing service called Napster.