Wikis can be considered as public domain knowledge sharing system. They provide opportunity for those who may not have the privilege to publish their thoughts through the traditional methods. They are one of the fastest growing systems of online encyclopaedia. In this study, we consider the importance of wikis as a way of creating, sharing and improving public knowledge. We identify some of the problems associated with wikis to include, (a) identification of the identities of information and its creator (b) accuracy of information (c) justification of the credibility of authors (d) vandalism of quality of information (e) weak control over the contents. A solution to some of these problems is sought through the use of an annotation model. The model assumes that contributions in wikis can be seen as annotation to the initial document. It proposed a systematic control of contributors and contributions to the initiative and the keeping of records of what existed and what was done to initial documents. We believe that with this model, analysis can be done on the progress of wiki initiatives. We assumed that using this model, wikis can be better used for creation and sharing of knowledge for public use.