Notifications of editors are mandated or recommended in some circumstances. If you are discussing another editor on a talk page it makes sense not to do so behind that editor's back. When you nominate a page for deletion, it makes sense to let the editor who created the page know that you would like to have the page they created deleted.
Discussing another editor
If you begin a discussion of another user on a common notice board, it is expected that you will notify the subject user by posting a message on their talk page (and/or through off-wiki email, if the subject has chosen to enable that function). There are two sides to most stories, and good faith requires the assumption that the subject of the complaint may have a valuable perspective to contribute.
The posting directions of various administrator noticeboards expressly note the expectation of notification. For example, the Admin's noticeboard requests that and ANI expects that you "inform other users and editors if they are mentioned in a posting, or if their actions are being discussed". Sockpuppetry investigations suggests users opening an investigation "[c]onsider notifying" all accused users.
These warnings, however, are not isolated, unrelated provisions applicable only to the pages containing them: editors are expected to offer the right of reply wherever appropriate. Particular notification requirements are manifestations of a broader judgment by the community that both sides of a dispute should be heard. Note also that the venue is not important; notification should accompany any public post you make requesting discussion of another user except when there is a reasonable expectation that they will see and be able to respond to your concerns in a timely fashion. Initiating a discussion at the talk page of a recently edited article would generally not require notification, but doing so at a noticeboard, wikiproject, or third party's talk page generally would. Friendly notification is also encouraged outside of antagonistic situations. As always, discretion and common sense are advised.
If a covered posting does not indicate that notification has been completed, other editors should consider checking the subject's talk page for an appropriate notification, and adding one if missing. Action should not generally be taken on an issue (aside from obvious vandalism and other unambiguous violations of community standards) until the subject has been notified and given a chance to explain their perspective on the matter.
- Wikipedia:Please do not bite the newcomers
- Wikipedia:Staying cool when the editing gets hot
- Template:Reply to
- Ordinarily, the onus is on you, the person raising the issue, to notify the editor you're complaining about. In rare situations, that may not be possible. For example, if the talk page of the editor you are complaining about has been semi-protected and you do not have a registered account, you will be unable to add a note on their talk page. See, e.g., User talk:TheOldJacobite. One answer to this, of course, is WP:SIGNUP. But if you just can't wait, ask another user to notify the defendant, or indicate the notification problem in your original posting so that someone else can do it for you.