Today user @sekao came back to a post of theirs, only to find it significantly altered by one of the moderators. Seeing your own words changed like that can be very disconcerting. I’ve reverted the change and apologized to @sekao. I’ve also contacted the mod in question to make them aware that this was inappropriate.
Moderators, admins, and people of trust level 4 can edit other people’s post. This feature should be used extremely sparingly. The only legitimate reasons I can think of right now or to fix broken markdown or broken links. Even then it’s a good idea to reply to the post so the original poster knows what’s up, e.g.
“Hi, I noticed you had a typo in the second link. I’ve updated it, can you check that it looks good?”
“I hope you don’t mind that I put your code snippets in code blocks. You can find a reference of the available markdown syntax at …link…”
This can also be a private message, but for the sake of transparency a reply to the original post is preferred.
(Wikis are a different story, I’ll mention those at the end.)
Changes to the actual text should be avoided. Honor the integrity of people’s word. This includes typos. How people use their language is part of their personal expression, and typos are part of that. “fixing” people’s writing can be offensive, and can make people self-conscious of their linguistic abilities.
Arguably removing illegal content can also be a legitimate use case, although in that case it’s probably better to flag and hide the post.
I’d like to take this opportunity to explain a bit more what can be edited by whom. For this you first need to understand the different access levels in Discourse. People new to the forum have “trust level 0”, this limits the features they are exposed to and the things they can do. As you spend time reading, posting, and commenting on posts, your trust level gradually goes up to “trust level 3”. Admins can manually grant someone “trust level 4”. Finally their are two flags: Moderator and Admin. Admins have access to everything, Mods have access to a subset of what the Admins can do.
Posts can be edited by the original poster, by admins, moderators, and people of trust level 3.
Posts can also be wikis. Wikis can be edited by anyone with trust level 1 or higher. Posts can be set to be wikis by anyone with trust level 3 or higher.