Navigation Bar:
Introduction
User contribution
Ratings and reviews
Tagging
Editorial control
User-generated content
Social networking
Implications
Another way users can contribute is through tagging content on your site, similar to the way users can tag their own photos on Flickr with any keywords they wish. Other people can then use these tags to navigate through content, for example, users can find all photos that anyone has tagged “Antelope Canyon.” This bottom-up approach to navigation (sometimes called a folksonomy) ensures that the site continues to adapt to real user needs, and the time users invest in tagging translates into loyalty.
The music recommendation site Last.fm uses tags to expose users to new music. Users can tag artists and albums with a variety of keywords (such as “classical” and “New Zealand” for Hayley Westenra), then browse other artists who share the same tags.

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Would tagging help your customers contribute to your site and better navigate your content? Tagging tends to work better for unstructured content that doesn’t already have a lot of associated metadata, so think about articles, images, and discussions. But it requires users to invest time to invent tags, so perhaps starting small is better to see if your customers will participate.
Next: Editorial control