A watchlist is a page which allows any logged-in user to maintain a list of "watched" pages and to generate a list of recent changes made to those pages (and their associated talk pages). In this way you can keep track of, and react to, what's happening to pages you have created or are otherwise interested in.
By default, pages are kept permanently on a user's watchlist until such time as they choose to 'unwatch' them. However, various options also exist for temporarily watching pages, from periods between one week and six months.
Watching a page means that the recent changes made to it will show up on your watchlist (Special:Watchlist), as well as changes to its associated talk page. Actions affecting watched pages (page moves, page creations and deletions, protection) also appear in the watchlist. For example, if you watch a page that does not yet have a talk page, you will see on your watchlist when someone creates that talk page.
If a page you have watched is moved to a new title, the new title will be automatically added to your watchlist. Even if the page is later moved back (and even if the page at the new title is deleted), the new title will remain in your watchlist along with the old one. If you notice mysterious nonexistent pages appearing on your list of watched pages, this is the most likely explanation.
When you view Recent Changes, Enhanced Recent Changes or Related Changes, entries relating to pages you are watching appear in bold text. This means that it may be beneficial to mark pages as "watched" even if you do not intend on viewing the Special:Watchlist page.
No user, not even administrators, can tell what is in your watchlist, or who is watching any particular page. Publicly available database dumps do not include this information either. However, developers who have access to the servers that hold the Wikipedia database can obtain this information.
For any particular page, it is possible to discover how many users have it on their watchlist. Under the Tools panel of the left sidebar go to Page information where "Number of page watchers" is shown. If the number is less than 30 it is not displayed for reasons of privacy and security.
Watching a page allows you to receive email notification of changes to it. To enable this feature, select "Email me when a page or file on my watchlist is changed" at Special:Preferences. (Currently, it is not possible to limit email notifications by page – you will receive notification when any page on your watchlist is changed.)
There are four ways to control which pages you have on your watchlist:
If you check "Add pages I edit to my watchlist" on the "Watchlist" tab of your user preferences, then the "Watch this page" checkbox will always be checked by default when you edit pages. Other similar options are "Add pages I create to my watchlist", "Add pages I move to my watchlist", and (for administrators) "Add pages I delete to my watchlist".
Twinkle has the option to automatically add articles it's used on to your watchlist (including PROD nominations, XfD nominations and reverts). To change these settings, go to Wikipedia:Twinkle/Preferences.
A new watchlist feature (Watchlist Expiry) was introduced in 2020. It enables users to optionally select to watch a page only for a limited period of time. (1 week, 1 month, 3 months or 6 months). This is done by clicking the hollow blue star icon and selecting the preferred time period in the dropdown which then appears. Once the chosen watch period has expired, the page is automatically removed from your watchlist. You can alter the watch period at any time, including switching from temporary to permanent watching, or unwatching completely at any time. Temporarily watched pages are usually represented by a half-filled blue star icon (as opposed to a fully-filled blue star, which represents a permanently watched page).
If you simply want to permanently watch a page as usual, you do not need to change any of your current processes.
When you are logged in to Wikipedia, a link, Watchlist, appears at the top of every page. This links to the special page Special:Watchlist, reporting recent changes to your watched pages. It is a list separated by days, ordered backwards according to the time of the edit.
Each line of a Watchlist (or Recent Changes page) shows details of each edit: whether minor (m), whether made by a bot (b), if a new page was created (N), if the edit was at an associated Wikidata page (D), the time, a link to the page, a link to the difference ("diff") made by the edit in question, a link to the page history ("hist"), the editor's user name or IP address, the increase (green) or decrease (red) in the number of bytes, e.g. (+76), (-490) and, if over 500, in bold: (+794), (-2,412), an arrow with a URL link to the specific section that was edited, and the edit summary. Wikipedia:Added or removed characters has more about the green and red numbers.
In August 2016 the English Wikipedia got ORES. When enabled at Beta, it displays a red r at edits which were flagged by the ORES system as potentially damaging. When disabled, the legend says r but no edits are marked. Beta features may change.
Pages that have been changed since you last visited them are shown with a green marker.
There are various options available to control how the list of changes is displayed:
It is possible to go beyond the standard options available in the "Watchlist" tab of your user preferences (see #Options section above). In particular, you can customize your watchlist using CSS, by editing your skin.css page. See Wikipedia:Customizing watchlists for details.
By default, an account can have only one watchlist. However, it is possible to set up watchlist-like functionality using the "Related changes" feature, in a way that effectively enables a user to achieve multiple watchlists. These are visible to anyone. To do this, create a page (normally in your own user space) containing links to the pages you wish to watch. Changes to those pages can then be monitored by going to the user page and clicking "Related changes". Note that in this case the talk pages corresponding to "watched" pages are not automatically included, and that changes to the user page itself will not be picked up.
Related Changes can also be used to monitor changes to pages belonging to a category, including the addition of pages to the category. However, the removal of pages from the category is not detected.
Custom tools are available to change the behavior of the watchlist, including User:MusikAnimal/customWatchlists, which allows watchlist entries to be categorized.
Watchlist notices are messages which are posted at the top of all users' watchlists, for example to publicize changes or discussions which are of importance for the whole editing community. Users are able to dismiss these messages when they have read them. The messages are placed via the message page MediaWiki:Watchlist-messages (editable by administrators only).
If you are experiencing a technical issue with your watchlist, such as the watchlist not updating after an edit has been made to one of your watched articles, the issue can be reported on Wikipedia:Village pump (technical).