The cloud refers to a public, or semi-public space on transmission lines. The cloud exists between the end points of transmission. Data that is transmitted across a WAN (see WAN) enters the network from one end point using a standard protocol suite such as Frame Relay and then enters the network cloud where it shares space with other data transmissions. The data emerges from the cloud, where it may be encapsulated, translated and transported in a great number of ways in the same format as when it entered the cloud. A network cloud exists because when data is transmitted across a packet-switched network in a packet, no two packets will necessarily follow the same physical path. The unpredictable area that the data enters before it is received is the cloud.