Many times you will see or read references to “Tags” - what does this mean?

Tags is an official snapshot release of the archetypes, client, maps and server based on branches/1.x (aka stable)

Tags also have a release version, such as v1.11.0, and are made approximately once a calendar year. This is the code base that many of the Linux packages (.rpm, .deb, et al.) use in their release cycle.

See also trunk, branch, latest, tags and stable