In simple terms, the more productive people participate in generating ideas, the more effective and valuable the contents will be. It is an architecture of people who interact globally with applications on the web to gather information. It is a very powerful concept of gathering explicit/implicit information for modern web 2.0 sites such as, blogs, wikis, tags and social bookmarks, social filters, XML syndication, and social networks.
Explicit participation is when users contribute information to improve their database. An example of a website that uses this is Amazon. The site allows users to rate products, upload images, and write reviews. It is a great way for online companies to attract customers who are looking for a specific product. They can read about it online and examine if the product is up to their expectations. It’s a great way for online companies to attract people to their website.
On the other hand, Implicit is a way of adding valuable information to a website from gathering information from the users themselves. A popular example of this can be seen being used in Facebook. A user who comments on their friend’s wall can be seen on the user’s page (e.g. Amiel commented on Johns wall).
Harnessing Collective Intelligence is like breaking the barriers that constraints people from sharing information. An interesting quote from Mike Wesch (2007), “ If you think about what one person can do, that’s interesting, but when you think about what 400 people can do when they all work together, that’s really interesting.” As an example, an intelligent person is able to engineer and make an ordinary car in a matter of years. However, a group of 1000 intelligent people are able to make the fastest car in the world in only a few months. This is possible through the collaboration and participation of numerous people in order to create something astonishing. According to Tim O’Reilly, a Web 2.0 is something that gets better the more people contribute to it. Google is a perfect example because it gets smarter every time someone makes a search and creates a link. The system learns from its users to improve the experience for everyone else.
Resources:
Amiel's Blog 
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