Each newsgroup is named according to a hierarchical convention. Additional terms are sometimes added, uniquely defining the newsgroup within a collection of others. An individual Usenet message. Also, the act of sending an individual Usenet message to a server that will display it in the newsgroup. A program that acts as a host for clients.
Clients post and read from servers.
A collection of posts that reference each other. Each response may be replied to as well. Threads may contain many branches and leaves, only a single branch, or none at all.