This paper studies Content Management Systems, specifically; collaborative authoring systems (Wiki), its definition, features, advantages, disadvantages, usage, and its applications in libraries. The paper also pinpoints a number of evaluation elements, and tries to present criteria that enables users to choose the best Wiki. The study compared 29 systems according to 34 elements and 7 criteria; system requirements, general features, data storage, security settings, technical support, usability, and outputs/extras. The results indicate that the best Wikis are; Tiki Wiki CMS Groupware, MediaWiki, and Wagn.