Tags
Tags are one of the important concepts of Web 2.0. It is a way of categorizing an area and largely done by the users themselves. For example if you like this post you could add it to your del.icio.us and give tag names that bring this post under those categories. You might tag them under “web 2.0″ or “categories” and so on. The closer and the more users start to assign the same tag name to a particular item, the more chance that someone looking for that item can get by searching through that tag name.
Tag names could either be system generated if there is taxonomy already available or it could be assigned by users. For example if you are building a site that gives details about living things there is already a taxonomy available and it is easy to just use that. But if you are building a website where users contribute information, it is best to allow the users to tag items by themselves. Gmail is one of the best and foremost examples of web 2.0. In Gmail there is no concept of having folders and dropping the mails into the appropriate one, rather mails are tagged with labels. So a mail could belong to more than one category, so it is possible to label them under those categories.
