Yes, the Stack Exchange network encourages community-based edits.
In the spirit of Wikipedia or other community-edited sites, we trust users – even anonymous visitors – to edit content here. There are some rules though that everyone should follow.
Why should I edit a post?
The most important reasons for editing a post is:
- Fixing obvious grammar and spelling mistakes.
- Making posts easier to understand, which helps both readers and the original poster (e.g. could prevent a question from being closed or downvoted)
- Adding additional information only found in comments, so that new visitors don't have to read everything
- Embedding or re-uploading images, fixing formatting, etc.
You can find more about these guidelines here, as well as on every edit page:
What should I not do?
When you edit other's posts, you're still editing their content. Therefore you should never …
- Change the meaning of the original post.
- Change subtleties that normally wouldn't matter (e.g. change spelling from British to American English, introduce your own writing style).
- Add something that doesn't relate to the actual post ("I have the same problem!" or "Here's something if you're interested … ").
If you understood the rules above, it's clear that you can't just go ahead and edit an accepted answer to state something completely different. If you disagree with an existing answer, vote it down, or provide clarifying comments. Or, add your own answer.
Who is going to review it?
Since anyone can edit on the Stack Exchange network, your edits will need to be peer reviewed by others if you don't have 2000 reputation yet. Once you reach 2000, you can edit posts without needing approval. Users with 5000 reputation can even access the queue of suggested edits in order to review them faster.
Edits that do not comply with the rules, when suggested by users below 2000 reputation, should be rejected or, if they've already taken place, rolled back.
Users with ≥ 2000 reputation are trusted to make their own edits without needing review, but they can of course still make mistakes. Therefore it is necessary that the community watches out for all edits and rolls back if necessary. You don't even have to search for these edits: Since editing a post bumps the question to the front page, it is likely that it will be seen by others.
It is good etiquette not to roll back an edit that actually improved a post – this would be considered rude. If you don't like the idea of having your posts edited for clarity, spelling, etc., then this site might not be the place for you.