Adding on to what at2004 quoted, Web 2.0 has a few trademarks. There are a number of major elements which are usually considered representative of Web 2.0

• Reliance on contribution of images, video or  information from users. For example, Flickr, Youtube and Yedda all rely on the reader's contribution.
• Appliance resemblance. Frequently Web 2.0 websites will resemble a layout usually attributed to desktop programs. This includes the ability to reload information without reloading the entire page (Google Calendar).
• Sleek and Simplified appearance.