HOW OPEN WIKIS REPAIR THEMSELVES

Every edit
can be undone.

Anyone can edit an open wiki. Anyone can also put it back.

A small server rack in a dim room with rows of glowing green and blue status lights, the kind of machine that runs software around the clock — AI-generated image, not a photograph of a real person or place.

Bots catch the obvious
People catch the subtle
History keeps it all
Layers of checking, not one gatekeeper

A wiki keeps every earlier version of every page. Bots, people watching recent changes and people watching their favourite pages use that history to undo damage, often within minutes.

THE SHORT ANSWER

Three layers,
each at its own speed.

Researchers describe wiki quality control as tiers:
machines first, tool-assisted people next, everyone else after.

BOTS

Seconds, not minutes

On English Wikipedia, the counter-vandalism bot studied in 2013 made nearly every revert within 30 seconds of the bad edit, and most within 5 seconds.

Who spots what

HISTORY

Nothing is really lost

Wiki software keeps every version. Reverting means restoring an earlier version from the page history; undo removes one edit and keeps later ones.

How a revert works

PROTECTION

Lock the busy pages

Pages that are attacked again and again can be semi-protected, so only accounts at least 4 days old with at least 10 edits can change them.

See the numbers

WHO SPOTS WHAT

What kind of
bad edit is it?

Pick a kind of problem edit to see which part of the system usually deals with it. The bar shows how quickly that layer tends to act.

Damage check

Choose a kind of editObvious nonsense or a blanked pageSuspicious edit flagged for reviewA wrong fact on a page someone watchesA subtle error on a quiet pageThe same page attacked again and again

Obvious nonsense or a blanked pageBot, in seconds

Fully automatic bots are fastest: in the 2013 study nearly every bot revert came within 30 seconds, most within 5. Bots tuned to avoid mistakes still miss many cases, so people follow up.

Suspicious edit flagged for reviewTool user, about a minute

People using queue-based review tools see pre-screened edits one by one. Most reverts with the most widely used tool came within 1 minute of the edit.

A wrong fact on a page someone watchesWatcher, minutes to hours

Registered users can watch pages and see each change. Manual reverts, where a person finds the edit themselves, mostly happened between one minute and 24 hours later.

A subtle error on a quiet pageWhoever notices

With no bot match and no watcher, damage waits for a reader to spot it. A 2007 study found about 11% of damage incidents lasted beyond an estimated 100 page views.

The same page attacked again and againProtection

An administrator can protect the page so only established accounts can edit it, or hold new users' edits for review before readers see them.

Sources: Geiger and Halfaker (WikiSym 2013), User:ClueBot NG statistics, Wikipedia protection policy, and the Wikipedia Signpost's summary of Priedhorsky et al. (GROUP 2007).

Based on Geiger and Halfaker's 2013 study of English Wikipedia reverts, the ClueBot NG bot's published statistics and English Wikipedia's protection policy. Other wikis set their own rules.

HOW A REVERT WORKS

Putting a page back,
step by step.

These steps follow MediaWiki's own help pages, the software behind most large wikis. Your wiki's buttons may be labelled slightly differently.

A locked glass-fronted wooden bookcase full of old leather-bound reference volumes with a small brass padlock on the doors — AI-generated image, not a photograph of a real person or place.

Open the page history
Pick the last good version, from before the bad edit. There may be several bad edits in a row.
Undo or restore
Use undo on the bad edit to keep later good changes, or edit and save the older version to restore it whole.
Say what you did
Write revert or rv in the edit summary with a short reason, so others can follow the change.
Check and watch
Look at the history again to confirm the damage is gone, then watch the page so you see the next change.

TWO NUMBERS WORTH KNOWING

Repairs are quick,
but not instant.

One figure on how fast reverts happen,
one on how often a reader meets damage.

12.4 min

Median time to revert, bot running

When the main counter-vandalism bot went down for days at a time in early 2011, the median time to revert rose to 21.4 minutes. The edits were still reverted in the end, just more slowly.

TIME TO REVERT · GEIGER & HALFAKER 2013

0.37%

Chance a typical page view was damaged

The Minnesota study put the probability at 0.0037, less than one-half percent, though it found the chance had been rising over time. About half of damage incidents were repaired on the first or second page view.

DAMAGED VIEWS · PRIEDHORSKY ET AL. 2007

Both studies looked at English Wikipedia, the largest open wiki. Smaller wikis have fewer watchers and bots, so damage can stay up longer; their recent changes list is often short enough for one person to check.

WHY BOTS MISS THINGS

Careful bots
leave work for people.

A counter-vandalism bot has to choose how sure it must be before it acts. ClueBot NG's operators publish the trade-off: held to a false positive rate of 0.1%, it catches about 40% of all vandalism; at 0.25% it caught about 55%.

That is why wikis keep human layers too. Older bots that matched lists of bad words caught only about 5% to 10% of vandalism, according to the same page, and subtle or plausible-looking errors still need a person who knows the topic.

A pencil eraser rubbing out grey pencil scribbles on a blank page of an open notebook — AI-generated image, not a photograph of a real person or place.

Questions

Questions people ask

Can anyone really edit a wiki?

On an open wiki, yes, though many pages carry limits. On English Wikipedia, semi-protected pages can only be edited by accounts at least 4 days old with at least 10 edits.

How fast is vandalism removed?

It depends on the kind. A 2013 study found bots usually reverted within seconds, while the overall median time to revert was 12.4 minutes with the main bot running and 21.4 minutes without it.

What is the difference between undo and rollback?

Undo removes one edit and tries to keep later ones. Rollback, for trusted users, instantly reverts all the latest edits by the last editor, with an automatic edit summary.

What does a watchlist do?

It shows recent changes only for the pages you have chosen to watch. It is for registered users, and your list is private.

Is a wiki page safe to quote, then?

Most damage is short-lived, but not all. A 2007 study found about 11% of damage incidents lasted beyond an estimated 100 page views, so check the page history and the cited sources first.

Where the facts come from

Updated 18 October 2026

Every editcan be undone.

Three layers,each at its own speed.

Seconds, not minutes

Nothing is really lost

Lock the busy pages

What kind ofbad edit is it?

Putting a page back,step by step.

Open the page history

Undo or restore

Say what you did

Check and watch

Repairs are quick,but not instant.

Careful botsleave work for people.