A network is a set of resources, events and/or agents which are all directly or indirectly related to each other within a specific context.
Network is an intentionally extremely generic term.
Agents could identify an unlimited number of networks, so it's often important to focus attention on relevant networks. For example, agents often identify networks which name or create important systems and systemic functions. (Systems exist within networks, and many networks contain many discretely identifiable systems.)
When referring to groups of agents, this description of network is intentionally more generic and flexibly relevant than any of the diverse types of groups (including communities and projects) which may create collectives or any other types of group agent.