Packet loss is a phenomenon that happens in both protocols but the user directly notices this only with UDP. TCP packets must be transmitted and received in order, checked for integrity and the correct reception of each and every TCP packet acknowledged by the peer. Should anything be amiss, such as a packet loss, the packet must be resent. This allows for highly "stable" connections and to have a general sense of the state of such a connection. If it goes stale, programs can initiate measures