What's a wiki?

I have created an account as a wiki site developer! Here is the link to my (yet to be developed) site:

http://elearning-in-action.wikispaces.com

And I have learnt that the difference between a BLOG and a WIKI is quite simple really. A BLOG is created by an individual who maintains the ability to block or deny access or comments by others whilst a WIKI actually invites and encourages others to add content or edit the site. Both Blogs and Wikis can contain text, images, videos, links to other websites, and so on. I have to admit to having an online look at other definitions and particularly liked the explanation offered at Answers.com: http://wiki.answers.com/Q/What_are_the_differences_between_a_blog_and_a_wiki

Using Wiki's in a classroom would allow experts to assist with content development. For example, in a primary classroom this could involve student's developing a "Healthy eating and physical activity" Wiki and receiving input from HPE specialist teachers, personal trainers, nutritionists and other health professionals, and linking to sites such as the Australian Institute of Sport. Following on from the Engagement Theory of Kearsley and Shneiderman (1999), assuming this topic has been chosen by the learners themselves, then use of a Wiki to guide the learning journey would involve the students working to construct support (Dimensions of Learning, Dimension 3) and take a position on the issue of health and physical activity as it pertains to them. Marzano and Pickering (2006, p. 160) state that student engagement is increased when students take a position on an issue they wish to support. I think a Wiki is a valuable tool for engaging students, scaffolding learning and monitoring understandings as they develop.