Gebruikers die niet ingelogd c.q. geregistreerd zijn worden anonieme gebruiker(s) of kortweg anoniem(en) genoemd. Zij kunnen artikels bewerken, tenzij deze niet (semi-)beveiligd zijn; in de bewerkingsgeschiedenis en elders wordt ter referentie hun IP-adres weergegeven.
On Wikimedia wikis, unregistered users were originally only at a minor disadvantage to registered users, but as time passed, more features have become unavailable to them. Unregistered users cannot move pages, using preferences, upload media, or maintain a watchlist. On the English, Indonesian, Portuguese, and Persian Wikipedias, they cannot create pages outside the "talk" and "draft" namespaces. Because IP addresses are sometimes dynamic, an IP-based user page can be impractical, and in fact it is disallowed on some wikis. Unregistered users are sometimes prohibited from participation in processes such as deletion and permissions debates, or can only participate on a restricted basis (e.g., can leave comments, but cannot vote).
Unregistered users also are not able to select the option of minor edit as this could allow a bad-natured user to make undesirable changes and not be spotted for some time.
Unregistered users are also sometimes referred to as anonymous users, or anons, as opposed to pseudonymous users (usernames on Wikimedia wikis are mostly pen names, not real names). However, this is ambiguous and, strictly speaking, incorrect. The public visibility of an unregistered user's IP address means that their geographical location and/or the organization from which they are posting can be looked up. Also, in extreme legal cases, the computer from which the user contributes could be identified through a subpoena to the ISP, which can eventually lead to identification of the user. In this sense, unregistered users are in fact less anonymous than registered users who do not reveal any personal information.
The creation of articles by IP editors was disabled on English Wikipedia after the Wikipedia biography incident in 2005.
In 2014, the creation of articles for IP editors were disabled on Persian Wikipedia. Between October 20, 2021 and April 20, 2022, editing for unregistered users were also disabled on the article namespace as part of an IP editing restriction study.
In 2019, the Wikimedia Foundation proposed hiding IP addresses of unregistered users from the public.
In 2020, the Portuguese Wikipedia disabled editing for unregistered users by a community vote.
- Anonymous users should not be allowed to edit articles (poll)
- Anonymous users should not be allowed to post external links (an essay)
- Association of Good Faith Wikipedians Who Remain Unregistered on Principle
- Discrimination against unregistered contributors (an essay)
- Research about Value of IP Editing
- Results of online interviews of unregistered contributors conducted in 2022 (summary slides):