Wikipedia:How to spot vandalism
Vandalism is a common problem on wikis, and Wikipedia is no exception. However, research by IBM found that as of early 2004, most vandalism suffered by Wikipedia was repaired within five minutes. This page is a collection of tips on how to find vandalism. Once you've found it, read how to deal with vandalism and revert the page to an earlier version.
Vandalism by non-logged in users
Most vandalism is carried out by users who have not yet created an account. There is an option on Special:Recentchanges to hide logged in users. This can be a way of filtering for only the edits most likely to be vandalism. Non-logged in users can not mark their edits as minor, so filtering minor edits out of recent changes using Special:Recentchanges/hideminor can also be useful in finding vandalism.
Vandalism by new users
New users are prime suspects for vandalism. Special:Contributions/newbies will show you the latest contributions by the people who most recently created a Wikipedia account. Be sure not to confuse a vandal with a clueless newbie.
Page creation vandalism
As well as vandalising existing pages, users will often create pages filled with vandalism. A good place to find these is Special:Newpages. The page size is shown next to each title so you can look particularly for the pages that are very small. Pages with ridiculous titles will also be easier to spot on Special:Newpages than they might be elsewhere. See Wikipedia:New pages patrol for an attempt to coordinate the checking of new pages.
Vandalism of high profile pages
Highly visited pages are the top targets of vandalism. The easiest way to spot these is to add them to your watchlist and check them regularly, particularly for anonymous edits. These pages include Wikipedia:About, Wikipedia:How to edit a page and Wikipedia:Welcome newcomers.
Any page linked to from the Main Page is likely to be a vandalism target. There are links on Wikipedia:Editing the Main Page to the related changes of each of the Main Page templates. Checking this will show you the changes to all the pages linked from the Main Page and is often helpful in finding vandalism.
Simple vandalism
Childish vandalism involves a vandal spreading the textual equivalent of graffiti over pages. This is usually extremely easy to detect, and quickly reverted. The most common types of this are toolbar experiments and page blanking.
Toolbar experiments are often on the border between vandalism and newbie tests. This is where users often push all the buttons on the editing toolbar and then hit save. This leaves behind text like
- '''Bold text'''''Italic text''[[Link title]]<math>Insert formula here</math>
The following searches will find all instances of such vandalism. On non-English Wikipedias, you should change the search to whatever text your toolbar options have been translated into.
Google:
Yahoo:
Also related to the toolbar are the example images and media formats. Checking which pages link to Image:Example.jpg and Image:Example.ogg can be useful in spotting vandalism.
Simple blanking of pages can be spotted by looking at Special:Shortpages and investigating why a page is zero kilobytes in size.
Spam
Wikipedia is occasionally spammed by users doing nothing other than adding inappropriate external links, either in an effort at search engine optimization or to drive traffic to a site. If you find spam on a large scale, you may be encountering a spambot. Spambots, and sometimes real humans, will spam many sites at once, often focusing on the smaller inactive wikis where their vandalism will go unnoticed for longer. There is no combined recent changes, so if you find a spammer, you may need to check the recent changes of every Wikimedia wiki. Asking a developer to run a search for you at m:Requests for queries can sometimes be a quicker way of finding it all. You can also request that a developer block a specific external link in the spam regex at m:Non-development tasks for developers.
Sneaky vandalism
Sneaky vandals are those users that think they can outsmart the wiki and put their little comments, misinformation, and typos on articles, without anyone noticing. Switching one number (often a date) for another and deliberately introducing typographical errors are their favorite tactics. Often this vandalism can be detected by looking at other edits by the same user, but we must be careful to avoid confusing sneaky vandalism with genuine corrections to an article. If you're unsure if someone is doing this, you can list it at the recent changes patrol page.
Userpage vandalism
Sometimes vandals and other problem users react to reversions and similar activities by vandalising userpages with insults, profanity, etc., just as childish vandals vandalise encyclopedia articles. Userpage vandalism is often, but not exclusively, performed by attention-seeking vandals. See meta:targets of trolls, for example.
Attention-seeking vandalism
The opposite of sneaky vandalism is attention-seeking vandalism. These users want attention, and will do anything to get it: they will write insults, use offensive usernames, replace articles with jokes etc. just to make you resentfully message them, and when you do that, they will use that as an excuse to replace your personal page with a story about your mother. So when you recognize this type of attack, try not to feed the troll by flaming him or her—just deal with it calmly and unemotionally—or leave it to someone else to do so if it's making you too angry. See Wikipedia:Dealing with trolls for further advice.
Vandalbot
A vandalbot is a program that attempts to vandalize or spam massive amounts of articles, blanking, or adding commercial links. In this situation, administrator intervention is needed and the IP address or complete IP range used by the vandal should be blocked, and all changes reverted systematically. See meta:Vandalbot for guidance.
Silly vandalism
Users will sometimes create joke articles or replace existing articles with plausible-sounding nonsense (example). This is usually easy to spot and is not always intended to harm. Sometimes the vandal will even announce the vandalism in the edit summary, ensuring that it will be spotted quickly.