Before I go into the details, I want to mention that recently there has been some venting in comments and some people retaliating to others' editing which is not acceptable.
For any discussion on the actions of another user these should be done in chat and in a respectable way. If necessary a moderator can be invited to join in the conversation. Comments should never be used for discussions.
No user should use the system to retaliate against another users actions. If there is an issue with another user, contact a moderator and discuss the issue with them.
Who can edit? Editing is a privilege of everyone on the site. Not just moderators.
Why should I edit? Editing is done to make things better, clearer, more effective -- never to change meaning. Editing improves the overall quality of the site and you also earn reputation for approved edits.
How does it work? Once an edit has been received it goes into a queue for high reputation users and moderators to approve or reject
What are some reasons my edit will be rejected? The main reason is if your edit does not provide any improvement e.g If it is only adding a single comma or it slightly improves one sentence but makes another sentence slightly worse etc.
What happens if too many of my edits are rejected? If you provide too many low quality edits you will not be allowed to suggest further edits for a period of time.
Refer to the post "What is the etiquette for modifying posts?" for general guidelines on etiquette for modifying posts.
If you are not happy with a way a post has been edited you have the option of rolling back a post to its original state. If both parties are still not happy with the state of the post then this should be taken to chat for a friendly discussion to reach a consensus.
Any unresolved issues should be taken up with a moderator and anything that needs to go further (rage, threats, spam etc.) can be done through the contact us link in the site footer on the bottom of every page.