Wikia

A diff is the difference between two versions of a page. It can be viewed from the page history: for every version there are potentially two radio buttons: the left column is for selecting the older version, the right column for selecting the newer one. Pressing "Compare selected versions" gives the difference between the two versions.

For special cases (the diff for a single edit or between an old and the current version) other possibilities are clicking cur or last in the page history or on the Recent Changes page. The diff is also shown during an edit conflict so you can see exactly what you need to reintegrate.

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How it looks

The two versions are shown side-by-side. In the old version paragraphs which differ are yellow and in the new version they are green. In left-to-right languages, the old version is on the left. This is reversed in right-to-left scripts. Text removed within a paragraph is shown in red on the old version. New text within a paragraph is shown in red on the new version. If a whole paragraph was removed or added, the text is not red but just black, while the other side is blank (white). Unchanged text is black on grey, only parts before and after changed text is shown.

The diff shows differences per line. Some editors find that adding manual line breaks improves the diff function.

As well as showing the difference between versions, the diff page has links to the user page and talk page of the users who edited both the last and current versions. Links to the users' contribution lists are also shown. For sysops, a rollback button is shown allowing them to revert from the new version to the old one. Note however that this is even shown when viewing the diff between the recent version of a page and a version older than the last version by an author other than the one of the most current version, in which case the rollback would not undo the change that is displayed. Thus if user A vandalized a page, and user B partially reverted that vandalism, the diff of the two together shows the remaining vandalism, but rollback reverts the partial repair by user B!

Edit summaries are also shown on the diff page. These appear in the row beneath the user names. If the user has used links in their edit summary, these act as links on the diff page as well.

In 1.4 there are also links to both versions, and the previous and next diff.

This example shows the top of the diff page, with the links described above.

Revision as of 22:32, Aug 03, 2003

Angela (Talk | contribs)
Edit summaries in diffs are great

Revision as of 00:10, Aug 18, 2003
Tim Starling (Talk | contribs) [rollback]
Reverted edits by Angela to last version by Anthere

When moving or copying a piece of text within a page or from another page, and also making other edits, it is useful to separate these edits. This way the diff function can be usefully applied for checking these other edits.

Width

After the table of differences, the latest of the two compared versions is shown fully.

In the case of the Classic skin with quickbar, the diff page does not have the quickbar, to provide more space. Therefore the diff page is also useful for viewing the page on full screen width, without changing the preferences.

With the Monobook skin the panels on the left are also on the diff page.

Page widening is more likely on a diff page, because there are two columns, but also because URLs (especially long ones) are not hidden.

URL

To do a comparison with the older page rendered below the table of differences, provide the URL as follows.

Open the revision of one page that you wish to compare to another, for example http://meta.wikimedia.org/w/index.php?title=Help:Diff&oldid=78722, and the revision of the other page that you wish to compare, for example http://meta.wikimedia.org/w/index.php?title=Main_Page&oldid=98420. Copy the oldid number of one page (&oldid=78722 in the first example) and replace the text oldid with diff: &diff=78722. Paste this string into the URL of the other page between that page's title and its oldid (&oldid=98420 in the second example), so you have something like this:

http://meta.wikimedia.org/w/index.php?title=Main_Page&diff=78722&oldid=98420

You may remove the page title (title=Main_Page in the example above) from the URL if you wish, but this is not necessary. The resulting diff will compare the given versions of the two pages [1].

To compare the current version of the page and a given oldid, you can put "current" after "diff=" instead of an oldid. For example, http://meta.wikimedia.org/w/index.php?title=Help:Diff&diff=current&oldid=124558

would compare the current version of this page with the version that has oldid 124558.

External link

http://cvs.sourceforge.net/viewcvs.py/wikipedia/phpwiki/newcodebase/DifferenceEngine.php

edit

Wikipedia-specific help

Template:Ph:Diff

This page is a copy of the master help page at Meta (for general help information all Wikimedia projects can use), with two Wikipedia-specific templates inserted. To update the main text, edit the master help page for all projects at m:Help:Diff. For Wikipedia-specific issues, use Template:Ph:Diff (the extra text at the bottom of this page) or Template:Phh:Diff for a Wikipedia-specific lead (text appears at the top of this page). You are welcome to copy the exact wikitext from the master page at Meta and paste it into this page at any time. To view this page in other languages see the master page at Meta.

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This page uses Creative Commons Licensed content from Wikipedia (view authors).

This text is stored on Wikia Community Central. Suggest changes here.

Each editable page on Wikia has an associated page history, which consists of the old versions of the wikitext, as well as a record of the date and time of every edit, the username or IP address of the user who wrote it, and their edit summary. You can access the history with a button in the drop-down Edit Button menu, along with "Rename." A page's history can also be viewed through the link in MyTools when visiting a page.

Quick summary:

The newest changes are shown at the top.
To view a specific version, click a date.
To compare an old version with the current version, click cur.
To compare a version with its predecessor, click last.
To compare to specific versions, tick the left-column radio button of the older version and the right-column radio button of the newer version, and then click the "Compare selected versions" button.
Minor edits are denoted as m.
Edits by bots are denoted as b.

Step-By-Step

Below is an example of a page history using the default Wikia skin (Note: The function of the page history screen is more or less the same in the Monobook skin):

Edits are shown from newest to oldest. Each edit starts on a new line and shows time and date, the contributor's name or IP, and the edit summary, as well as other diagnostic information.

Let's look at some of the functions of this page:

The page name.
These links take you to the most recent edits (Latest), oldest edits (Earliest) or the next or previous page of edits (Next n / Previous n). Note that the black text in brackets will become links, when applicable.
The blue numbers list the number of edits displayed on a page - 20, 50, 100, 250 or 500. A higher number increases the length of a page but reduces the number of display pages if more than one. The number you select replaces n in the links to the previous or next pages e.g. (Next 100 / Previous 100).
(cur) takes you to a 'diff' page - any page showing the difference between that edit and another version of the page history. In this case the diff page is comparing the selected version and the current version. The current revision appears below the changes, so you can see how the page is now rendered.
(last) takes you to a diff page showing the changes between that edit and the previous version. The most recent version (the one on the same line as the "last" you clicked on) appears below the changes, so you can see how the page was rendered.
The two columns of radio buttons can be used to select any two versions on the page. Let's say you want to compare the versions corresponding to numbers 10 and 11 on the image. First, click the left radio button next to number 11. The right column of buttons will then fill as far as number 11. Then click the right button next to number 10. Finally click Compare selected versions. This takes you to a diff page showing the changes between the two versions. The most recent version (in this case number 10) appears below the changes, so you can see how the page was rendered.
This gives the time and date of the edit, expressed in local time according to the preference setting. The date and time link to the version of that day and time. Thus the first line links to the version that was current at the time of loading this revision history, and therefore the result may differ from that of following the link on the page margin to the current version. Even if the page has not changed in the meantime, the MediaWiki:Revision-info message appears.
The username or IP of the contributor appears here.
This is the edit summary. It is the text the user wrote in the edit summary box (below the edit box).
This edit summary begins with an arrow link and grey text. This means the user has only edited a section of the page (named in the grey text). This text is automatically added when you edit a section. A standard edit summary can be added by the user. This appears in black text.
m stands for minor edits (small corrections to a page). These help you understand the type of changes that have been made.

If the "move page" feature has been used in the past to change a page's name, the entire edit history of the article, before and after the move, is shown. The old title becomes a redirect and loses its edit history. After merging two pages, typically one becomes a redirect. In this case the revision history of the redirect is kept.

Edits made to deleted pages are not kept in contributor's User contribution pages. However, the revision history is kept and can be retrieved by an administrator, who can also undelete the page.

Going Deeper

History and Followed Pages

If one views the history of a watched page directly, without first viewing the page, the edit at the top (the most recent one) may be marked with update marker "updated (since my last visit)" (or the content of MediaWiki:Updatedmarker); this applies if the edit was made by someone else and you have not viewed the page (while logged in) since it was made. The positioning of the message, suggesting that it is a property of an edit rather than a property of the page, is somewhat misleading, because not all edits which have not been viewed yet are marked.

Creating Feeds

Feeds (RSS and Atom) for the history of a page are obtained by clicking the "RSS" or "Atom" links in the toolbox in the sidebar. You may then use a feed aggregator or other tool to monitor changes to the page.

The RSS2Wiki extension will allow you to include the RSS feed into another wiki page.

Linking to a Specific Version of the Page

Yes. If you want the current version, click "Permanent link" in the toolbox in the sidebar. If you want to link to an older revision, click on the correct date for the version on the page history to view the old version of the page.

In both cases the URL of the version in the browser's location/address bar is suitable for use to permanently reference this version.

Note:

If a page contains a time-based variable, its rendered content will use the current date/time, not the time as it was when the revision was saved.
- Templates and images will vary if they are referred to with an expression containing a variable depending on time
The current versions of templates and images are used; if they have been revised, the page may look different than it was at the time the version was saved.

Exporting Page History

Special:Export produces an XML-file, without the MediaWiki user interface, with the wikitext of the current and optionally all old versions of one or more specified pages, with date, time, user name, and edit summary. How it is displayed, e.g. with or without XML tags, and with or without applying new lines, depends on the browser. Some browsers show "+" and "-" links to view or hide selected parts. Alternatively the XML-source can be viewed using the "view source" feature of the browser, or after saving the XML file locally, with a program of choice.

The feature also allows searching for a text in all versions of one or more specified pages.

Image History

An image or other media file can be replaced by a different image, by uploading a new image file with the same name. All versions are kept. The image history listing forms part of the image description page, which appears when you click on the image. The image history of the current and previous versions. Older versions of the image can be restored.