Glossary of Usenet terms

Quick definitions for terms you will see in clients, indexers, and provider documentation.

Article: A single post on Usenet, with headers and body. Binaries are split across many articles.
Backbone: A large upstream news network that peers with other servers and carries high retention.
Completion: Whether all parts of a file are still available on the servers your provider can reach.
Connection limit: Maximum parallel NNTP connections your plan allows (e.g. 10 or 25).
Header: Metadata for an article: subject, date, from, message-id, etc.
Indexer: A service that catalogs posts and publishes NZB files pointing to articles.
NNTP: Network News Transfer Protocol—the protocol clients use to talk to news servers.
NZB: A small XML file listing message-ids so a client can fetch a specific set of articles.
Newsgroup: A named channel where articles are filed. See what are newsgroups.
Par2 / parity: Recovery files that let clients repair missing chunks after download.
Propagation: How articles spread from one server to others across the network.
Retention: How long a server keeps articles before deleting them.
RAR / archive set: Common compression split across multiple volumes for large binaries.
SSL / TLS: Encryption for NNTP. Hydra requires SSL on port 563.
Usenet server: A host that stores articles and serves them via NNTP. See what is a Usenet server.