This help page is a how-to guide. It details processes or procedures of some aspect(s) of Wikipedia's norms and practices. It is not one of Wikipedia's policies or guidelines, and may reflect varying levels of consensus and vetting.

Shortcut WP:CDLG

A diff is a permanent link to a single edit or set of edits, showing the difference between the before and after versions.

If you contribute an argument to a page like requests for comment, requests for arbitration or the incidents noticeboard for administrative attention, it's essential to give evidence for your claims in the form of diffs and/or other links. Without such evidence, you will be taken less seriously. If you simply claim that "editor X has posted several personal attacks on talkpages" or "editor Y is edit warring on George W. Bush", you may be ignored, or told "diffs or it didn't happen".

The most useful evidence consists of diffs to individual edits and links to page sections. Avoid linking to entire talkpages, as they are too long and diverse to be helpful. Linking to parts of a page history or an editor's contributions can be done, but is a bit complicated; see Timestamp limits below.

Find the page which contains the edit you want to refer to. Click on its View history tab. Find the edit in the history list. (If that's a problem, clicking on the word (prev) in the list will let you read the edit.) Right-click on its "(prev)" button and select "Copy link address" or "Copy Shortcut" depending on browser, O.S., etc. The diff you want is now in your clipboard.

Find the page which contains the section you want to refer to. Click on "Permanent link" in the "Toolbox" in the lefthand sidebar. Go to the page's Table of Contents. Right-click on the name of the section you want to use, where it appears in the Table of Contents, and select "Copy link address". The section link you want is now in your clipboard.

 Warning This does not work fully as intended. It links to the upload log (or any other type of log) and a date to specify a search for on that date and prior, but no specific date range can be specified.

Logs are subject to change, but a form of permanency can be achieved by specifying the time span over which one inquires. For example, by adding ?type=upload&wpdate=YYYY-MM-DD. (Note, this date reflects the UTC server time).

• ((fullurl:Special:Log|type=upload&user=&page=&wpdate=2019-09-05&tagfilter=)) will link to a log of all the images uploaded on 5 September 2019.

More complicated linking can be achieved using timestamps in the linking URLs. These take the form YYYYMMDDhhmmss, where YYYY is the year, MM is the month, DD is the day, hh is the hour, mm is the minutes, and ss is the seconds. For example, 20070814233520 is 23:35:20 on 14th August 2007. This allows specific linking to parts of a contributions list or a page or user log, as shown above. One use of these timestamps is to link to a specific range of edits by a user.

To link to a range of sequential edits by a user, find the date and time of the last edit and generate a timestamp as above. Then set the limit to the number of edits required. The results will change if any of the edits are deleted (e.g. if one of the articles that was edited gets deleted). An example of this is:

• ((fullurl:Special:Contributions|offset=20071015005300&limit=11&contribs=user&target=Carcharoth)), which generates a link to a list of 11 sequential edits up to 00:53 on 15th October 2007, selected to show a particular type of editing.

Similarly, a permanent diff to a specific revision history of a user page may be generated:

• http://en.wikipedia.org/w/index.php?title=User_talk:Bishonen&action=history&limit=25&offset=20090417223300

This would give the last 25 items in the revision history of User talk:Bishonen before 2009-04-17, 22:33:00 UTC (22:33 UTC on 17 April 2009).

1. The best way is using ((Diff2)). For instance, ((Diff2|512088043|example edit)) gives example edit.
2. Diffs and links will work if they're simply pasted into your text like this: http://en.wikipedia.org/w/index.php?title=Deep_End_Live!&diff=prev&oldid=512088043.

   Or you can make them neater by putting single (not double) square brackets round them. Typing this: [http://en.wikipedia.org/w/index.php?title=Deep_End_Live!&diff=prev&oldid=512088043] will give a note like this: [1].

   Or you can make them elegant by wrapping them into a word in your text. Typing this: [http://en.wikipedia.org/w/index.php?title=Deep_End_Live!&diff=prev&oldid=512088043 example edit] will give example edit link. Notice the space between the link and the wrapper word.

3. Or you can use ((Diff)): ((Diff|Deep End Live!|prev|512088043|example edit)), which gives example edit. The template's documentation gives examples of the various formats available.

When using URLs (and not the two templates) the http:// must be used. However, the page name after the title= part only serves to make the URL more readable - it can be left out (http://en.wikipedia.org/w/index.php?oldid=191637801), or even manipulated without affecting the target of the link. (For example, http://en.wikipedia.org/w/index.php?title=Good&oldid=191637801 actually points to a version of the article Evil.) This is the reason why ((Diff2)) works, and has occasionally been abused to deceive casual readers.

The ((fullurl:PAGE_TITLE|other=URL parts&go=here)) syntax expands to a http:// link and can be used in almost all cases that a http:// link can be used, but is shorter and will not inadvertently bounce users between the two servers.

Also, be aware that diff links can also be created between non-consecutive versions (see Help:Page history). Thus, a diff link might show the changes from several users at once, but only one of them will displayed on the right hand side. It is even possible to create diff links which compare versions of different pages. Example: //en.wikipedia.org/w/index.php?title=Phillips,_Nebraska&diff=179085783&oldid=179088483 compares a version of Phillips, Nebraska with a version of Hordville, Nebraska. This can be used to highlight copy and paste actions. Another possible use is to create a "diff" for a page creation by comparing to a blank version of another page. Example: The creation //en.wikipedia.org/w/index.php?title=Barack_Obama&oldid=2814496 can be compared to the blank //en.wikipedia.org/w/index.php?title=Wikipedia_talk:How_to_edit_a_page&oldid=44 by inserting =44&diff after oldid in the creation url: //en.wikipedia.org/w/index.php?title=Barack_Obama&oldid=44&diff=2814496.

To the URL of the diff, append &diffonly=1

• a regular diff, showing the change and the resulting version of the page

• only the diff, without showing the page

• Help:Page history
• Help:URL
• User:Snottywong/diffconverter
• Wikiblame, a tool that allows to find a diff (an edit) that introduced a specific text into a page.
• Meta:Help:Diff#Diff link (can be used to add a diff link in the edit summary)
• ((diff)), the Diff link template