Web 2.0 is so powerful to dominate our new life on the Internet. del.icio.us is the shared bookmark service that adopts the concept of web 2.0 and Flickr is also a good example of web 2.0.
They are using the concept of tags. We can attach tag to pictures or bookmarks. Tag is like keyword that presents the meaning of something. Before, I only classify something to one category. Now, We can classify pictures or bookmarks to several category that using tags.
It's so great!