Watching pages

# Overview
Anyone with an account may choose to be notified when a certain page changes using the 'watch' feature and 'my watchlist'. MediaWiki does not let people 'own' pages; however, the watchlist feature, along with the ability to revert changes, keeps interested users involved in particular pages without the drawbacks of giving someone absolute control over a page.

# Controlling which pages are watched
When logged in, there is a link "watch" or "unwatch" at the margin of each non-dynamically-generated page. By clicking on that link, you add the current page and the corresponding talk page (or if it is a talk page, that page and the corresponding non-talk page) to the collection of pages you "watch", or remove them, respectively. (All additions to and deletions from the list of watched pages apply to the non-talk page / talk page combination: one can not watch one and not watch the other.)
When saving an edited page, the new watch status (do or do not watch) is determined by the "Watch this page" checkbox.
If one activates the user preference "Add pages you edit to your watchlist", the checkbox on the edit page will automatically be checked, so unless it is unchecked before saving, the page will be watched upon saving.
A list of watched pages, with the possibility of en masse unwatching pages by clicking checkboxes, can be done conveniently using :Watchlist&magic=yes, also available as link at the top of the Watchlist.

# Effects of watching a page

## Watchlist
When the user is logged in, every page has a link to the user's watchlist, also accessible by the link Special:Watchlist. It approximately functions as a custom recent changes just for pages that you watch. It gives a list of all watched pages, ordered backward according to the time of the last edit of the page, optionally up to some cutoff time.
The enhanced watchlist is equal to the enhanced recent changes,  restricted to watched pages, and without the bolding.
Each line shows details about the last edit (with the enhanced watchlist multiple edits): the day, whether minor or major, the time, a link to the page, the difference between the current version and the last one, the history, the user name and the edit summary. By default, each line also shows the change (+/-) in bytes since the last version (see below, What do the colored numbers mean?). There is currently no way to exclude minor changes from the watchlist.
Note that in the non-enhanced watchlist for every edited page only information about the last edit is shown. For example, if the last edit was minor there is no indication whether there have also been major changes recently. Since one is typically interested in all changes since one last checked, the history of the page needs to be checked.
Moving a watched page does not show up on the watchlist; after the move both the old and the new name are watched.
The watchlist is only one of the features with regard to watching pages; even without ever using it, specifying pages to watch is useful.

## Recent and related changes
In Recent Changes, Enhanced Recent Changes, and Related Changes, watched pages are bolded.

## Update marker
From MediaWiki 1.5 the message "updated (since my last visit)" appears in lines on the watchlist, on the recent changes page, and in the page history. Note that to reset this (clear the notification flag) one has to be logged in when viewing the page. The message has CSS class "updatedmarker".

## E-mail notification
Note: This feature is not available on wikipedia.org .
From MediaWiki 1.5 , depending on preference settings, you get an e-mail after a watched page has been edited by somebody else. This will not be repeated until you view the page. Note that you have to be logged in when viewing the page, otherwise you will not be notified of further changes.
Optionally this notification system can ignore minor changes.
See also MediaWiki: email notification.
Having a separate email for every edited page that one likes to watch in the sense of the other watch features, may be too much. New features are being proposed and developed to deal with this: the option to have e-mails sent, after a delay, with a list of edited pages, and/or the possibility to specify a subset of watched pages for e-mail notification.
For the latter, as a workaround, one may be tempted to log in under a different username just to specify a different (typically smaller) watchlist for e-mail notification. However, after viewing a page under one username, one would have to clear the notification flag for that page for the other username too.

# Watching wikitext vs. watching the rendered page
Note that watching pages detects changes in the wikitext only, not all changes in the rendered page, see history of the wikitext vs. history of the rendered page. One can additionally watch the templates used, and the templates used by these templates, etc. This also limits the effect of watching an image page or category page. Oddly, it is not possible to watch an image. Also, it is not possible to watch a category in the sense of being notified if pages are added or removed. With "related changes," additions can be detected; for removals, one has to watch all pages in the category.

# Watching a non-existing page
You can also watch a non-existing page. Then you see it on your watchlist when somebody creates it. This is often the case for talk pages. For a non-talk page, if the page has a (broken) link to it, press that link and press "Watch" (depending on the skin you may have to press Cancel before getting the link Watch). You can also go to the non-existing page using the URL.

# Deletion of pages
Oddly, the deletion of a watched page is not shown in the watchlist!
However, :Watchlist&magic=yes shows all watched non-talk pages, including the deleted ones. Since the pages in the list are given in the form of links, deleted ones are easily identified, especially if you normally do not watch nonexisting non-talk pages.
However, talk pages are not listed separately, hence deletion of a talk page can not be detected in this manner. In particular talk pages of template pages are vulnerable: content that is valuable enough for a non-talk page could be put here, instead of putting it in noinclude tags in the template page itself.

# Related changes feature
The "Related changes" can be used to set up watchlist-like functionality, as explained below.
Pages with links (possibly specially created for this purpose, e.g. as subpages of one's user page) can be used with Related Changes as a collection of separate "watchlists". Note however that unlike My Watchlist, Related Changes does not automatically include talk pages; to watch also the corresponding talk pages, links to them also have to be in the page on which Related Changes is applied. If the links to the talk pages are put just for this purpose, a blank space as link label can be used, which makes the link invisible and ineffective, except for Related Changes. See e.g. w:List of astronomical topics and its wikitext, with items in the form ] ] showing up as just Main Page  .
Note that Related Changes does not detect an edit in the page itself and its talk page. Either include a self-link and a link to the talk page in the page, or put the page in another "special watchlist", or in one's standard watchlist.
Such pages can use the template mechanism to include other pages. However, see Pollution of categories.
Watching pages in a category by applying Related Changes to the category has a major drawback: removal of a page from the category is not detected.

# Watching a category or an image
Watching a category or an image means watching the editable part. Adding a page to, and removing a page from a category is not reported. The same applies for changing the image.

# CSS
As an alternative or in addition to using the watchlist feature, one can also define a user style for links to selected pages, putting in one's CSS a list of lines like:
- a {color:  white; background: red; font-size: 150% }
This works in Opera, but not in IE.
On the (Enhanced) Recent Changes page it works like the bolding feature mentioned above, but it is more versatile, e.g. allowing extra emphasis on pages one is very interested in, or different styles for different categories of interesting pages. Furthermore, it also works on user contributions pages, and on regular pages (also for piped links, but not for indirect links through a redirect). It also applies, less usefully, for the section editing links in the page itself.
To highlight links to the given page also from other websites, including interlanguage links, use instead of the above:
- a { .. }
Note that the full URL is needed, even to highlight links from the same project, even though the HTML code uses the relative URL /wiki/pagename.

# Privacy of watchlists
Ordinary users or administrators cannot tell what is in your watchlist, or who is watching any particular page.  Developers who have access to the servers that hold the Wikipedia database can figure out this kind of information.  Publicly available database dumps do not include this kind of information.