Search terms are like keys to documents or to any other type of content. In our days, not only the volume of available documents is increasing rapidly, but also the size of the keychain is growing.
Before we start to discuss how to organize/index the documents themselves, we should first talk about methods to organize the keys.
Take a look at these three approaches:
On the left-hand side you can see a nice example of implicit semantics. The old receptionist knows exactly which key fits into which lock. This knowledge is implicit and can be remembered by the shapes of the keys. Before the old receptionist has retired and the knowledge would have gone, labels have been attached to every key. The semantics of the keys has become more explicit, but this is still quite ambiguous (as visualised in the center column). There is no index of all the labels and colours being used, neither an explicit methodology how new keys should be labeled. As the hotel grows, the labeling system becomes quickly a mess. On the right-hand side the solution for this problem is offered: Not only the semantics of the keys becomes more explicit, but also the semantics of the semantics. For instance, the position of a key represents the position of the room, which can be unlocked by this. The number of the row of the key cabinet represents the storey of the room being unlocked, etc.
This methodology in order to organise keys helps to orientate and to remember; it can be explained with low effort to any new receptionist and it can be scaled-up in case your hotel should grow in the next few years.
About the Social Semantic Web 