Wikipedia:Node (networking). Un nodo. Ein Knoten.

In networking this usually means a host, a machine, or at least a router. A hop along a route. See also Routing.

In PSYC we specifically define a node as follows:

Node

A PSYC application which is reachable and interconnected with other PSYC applications is called a node in the PSYC network. A node always has both a protocol root and an entity root. It may also provide further entities of varying kind.

It can therefore be a server, a client, a router, a bot, a service or something else or any combination of these.