An edit conflict is a computer software problem encountered on wikis. An edit conflict occurs when a shared document is being edited by more than one person at the same time and a conflict is generated. One person attempts to edit the document, but upon trying to save the new version, another person has already modified the document in the intervening time period, thus causing a difference between the attempted edit and the already-made edit that must be resolved manually. The software will then generate an "edit conflict" error message. According to computer writer Gary B. Shelly, "many wikis will block the contributor who is attempting to edit the page from being able to do so until the contributor currently editing the page saves changes or remains idle on the page for an extended period of time."

The problem is common when working on heavily-edited articles on Wikipedia

Wikipedia

Wikipedia is a free, web-based, collaborative, multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its 20 million articles have been written collaboratively by volunteers around the world. Almost all of its articles can be edited by anyone with access to the site,...

, such as those about a "current event" or a "person suddenly in the news", or on other "high traffic pages".

If a significant amount of new text is involved, the editor who receives an "edit conflict" error message can cut and paste

Cut and paste

In human-computer interaction, cut and paste and copy and paste offer user-interface interaction techniques for transferring text, data, files or objects from a source to a destination. Most ubiquitously, users require the ability to cut and paste sections of plain text...

 the new text into a word processor or similar program for further editing, or can paste that text directly into a newer version of the target document. Simple copyediting can be done directly on the newer version, and then saved.

For example, edit conflicts can arise when two or more editors are working on Google Sites

Google Sites

Google Sites is a structured wiki- and web page-creation tool offered by Google as part of the Google Apps Productivity suite.- History :Google Sites started out as JotSpot, the name and sole product of a software company that offered enterprise social software. It was targeted mainly at...

.

A similar problem can occur when two or more users simultaneously edit the same file in a revision control

Revision control

Revision control, also known as version control and source control , is the management of changes to documents, programs, and other information stored as computer files. It is most commonly used in software development, where a team of people may change the same files...

 system that does not have file locking

File locking

File locking is a mechanism that restricts access to a computer file by allowing only one user or process access at any specific time. Systems implement locking to prevent the classic interceding update scenario ....

. See Concurrent Versions System

Concurrent Versions System

The Concurrent Versions System , also known as the Concurrent Versioning System, is a client-server free software revision control system in the field of software development. Version control system software keeps track of all work and all changes in a set of files, and allows several developers ...

.