Contributors, registered or not, can take advantage of features available in the software that powers Wikipedia. The "History" page attached to each article records every single past revision of the article, though a revision with libelous content, criminal threats or copyright infringements may be removed afterwards. This feature makes it easy to compare old and new versions, undo changes that an editor considers undesirable, or restore lost content. The "Discussion" pages associated with each article are used to coordinate work among multiple editors. Regular contributors often maintain a "watchlist" of articles of interest to them, so that they can easily keep tabs on all recent changes to those articles. Computer programs called Internet bots have been used widely to remove vandalism as soon as it was made, to correct common misspellings and stylistic issues, or to start articles such as geography entries in a standard format from statistical data.