For questions about the suggested edit process, which allows users without editing privileges to "suggest" edits, to be reviewed by users with editing privileges.
Users with 2,000+ reputation have the privilege of editing any question or answer.
Users with accounts (both registered and cookie-based) who have not reached the level of 2000 reputation (or 100, for community-wiki posts), as well as users with no account, are allowed to suggest edits. These are not applied immediately, but go into a queue where users who have edit privileges can vote to approve or reject them, or alternatively perform an improved or completely different edit.
The suggested edits feature also applies to users who don't have 20,000 reputation to suggest edits to tag wikis. 5,000 reputation is needed to review suggested edits to tag wikis, but 20,000 reputation is required to make binding edits without approval or to improve those edits.
All three of these rep thresholds vary between sites in private beta, public beta, and graduation.
If your edit gets approved, you get 2 rep. (However, you can earn at most 1000 reputation points through suggested edits.)
If your edit is rejected, a reason will be displayed on the suggested edit page. You can track your suggested edits under the suggestions section of the Activity tab on your account profile.