When no license is specified, an implied license to read and add content to a wiki may be deemed to exist on the grounds of business necessity and the inherent nature of a wiki, although the legal basis for such an implied license may not exist in all circumstances. Wikis and their users can be held liable for certain activities that occur on the wiki. If a wiki owner displays indifference and forgoes controls (such as banning copyright infringers) that he could have exercised to stop copyright infringement, he may be deemed to have authorized infringement, especially if the wiki is primarily used to infringe copyrights or obtains a direct financial benefit, such as advertising revenue, from infringing activities. In the United States, wikis may benefit from Section 230 of the Communications Decency Act, which protects sites that engage in "Good Samaritan" policing of harmful material, with no requirement on the quality or quantity of such self-policing. It has also been argued, however, that a wiki's enforcement of certain rules, such as anti-bias, verifiability, reliable sourcing, and no-original-research policies, could pose legal risks. When defamation occurs on a wiki, theoretically, all users of the wiki can be held liable, because any of them had the ability to remove or amend the defamatory material from the "publication." It remains to be seen whether wikis will be regarded as more akin to an internet service provider, which is generally not held liable due to its lack of control over publications' contents, than a publisher. It has been recommended that trademark owners monitor what information is presented about their trademarks on wikis, since courts may use such content as evidence pertaining to public perceptions. Joshua Jarvis notes, "Once misinformation is identified, the trademark owner can simply edit the entry." See also Comparison of wiki software Content management system CURIE Dispersed knowledge List of wikis Mass collaboration Sweble Universal Edit Button Wikis and education Notes References Further reading External links Exploring with Wiki, an interview with Ward Cunningham by Bill Verners Murphy, Paula (April 2006). Topsy-turvy World of Wiki. University of California. Ward Cunningham's correspondence with etymologists WikiIndex and WikiApiary, directories of wikis WikiMatrix, a website for comparing wiki software and hosts Hawaiian words and phrases Hypertext Self-organization Social information processing Articles containing video clips