Canon is a term used to describe the ideas and materials considered officially part of Star Army's setting. In general, we try to include all roleplay as canon.
The reason canon exists is so that the Star Army universe can stay internally consistent so that our roleplayers can be have a shared, mutual understanding of what the Star Army universe is like. In other words, it keeps us on the same page.
Canon elements must be acknowledged by and accounted for by other roleplayers on SARP. For example, if it's canon that a planet has a defense system, an enemy fleet would not be allowed to just land on the planet without dealing with the defenses first. Or if your character crashed a spaceship on a planet in your roleplaying thread, the debris should be noted on the planet’s wiki page and can then appear in other roleplay threads (maybe they can salvage it).
On Star Army, the wiki is used to keep track of canon, and is the primary repository of what is canon. This is followed by the roleplaying forums, which can be used as a secondary source of canon. Wes is the manager of the Star Army setting, and has the final word on what is considered canon.
On Star Army, there are multiple levels of canon:
Things are considered “hard canon” if they have an approved wiki article that is based on events in the roleplay. They are part of the universe's continuity (e.g. the series of events that make up the timeline). For example, the history of the YSS Eucharis or the The Freespacer Genocide. Star Army is a long-running roleplay so a lot of our history found on the wiki actually occurred in the RP, making it hard canon. You can tell these type of articles because they often have links in the footnotes to the related roleplaying threads (and we encourage you to do that).
Hard canon should never be changed unless absolutely necessary, as this could invalidate people's RP. Such a retcon can only be approved by the Setting Manager.
Firm canon consists of content that has been approved as canon on the wiki, but has not actually been featured in the RP. The wiki is considered to be higher level canon than the forum RP because it's the shared space that all forum RPs are based on.
Firm canon can be changed if needed, as there's some flexibility given by the fact that no one has used it yet, but it should only be changed if necessary, because players and GMs might be making plans based on it. Once it's used in RP, it becomes hard canon and should not be changed.
Soft canon consists of roleplay that happened but was not added to the wiki. Some Open RP may be considered soft canon (as it might not make it to the wiki).
Forum RP that is not on the wiki is considered below wiki canon because the wiki is the repository of canon. Therefore, if the events and content from an RP are not shared (via the wiki) with the rest of Star Army community, other GMs cannot reasonably be expected to base their RP on those.
Ideally all soft canon should become hard canon by writing about it in the wiki and getting the article approved (if necessary). This should be done as soon as possible by the GM, thread OP, or any other person involved in the RP. Failure to do so could result in roleplays that contradict each other.
Non-canon is information that is not considered “official” for Star Army. This includes things like alternate universes; wiki articles that are not yet approved, and threads marked as non-canon. Reasons that RP threads might be considered non-canon include non-canon elements (e.g. unapproved tech, stuff Star Army lacks rights to), or major events and changes to the setting that were not discussed/approved with the people responsible for the affected factions or characters.
Note: As of 2016, wiki works in progress should go in the wip: namespace.