Within most client-server architectures, a horizon of connectivity is the boundary that limits access to server-based resources when the client is disconnected from the network. Client-server applications such as desktop email clients, which provide offline functionality (typically only a subset of that possible while connected), may be referred to as operating beyond the connectivity horizon. Such clients work by queuing changes made locally for synchronization with a server at a later time. Certain peer-to-peer applications may also be considered to function beyond the horizon of connectivity, in that they queue changes for later synchronization with other peers.