1. <messaging> One point-to-point transmission in a series required to get a message from point A to point B on a store and forward network. On such networks (including UUCPNET and FidoNet), an important inter-machine metric is the hop count of the shortest path between them. This can be more significant than their geographical separation.
2. <networking> One direct host-to-host connection forming part of the route between two hosts in a routed network such as the Internet. Some protocols place an upper limit on the hop count in order to detect routing loops.