Why do we say the web is fragmented? We have to understand that all directed networks break into the same four continents. The continents include central core, IN, OUT, tendrils and islands. (What? That was 5 of them! Tendrils and islands are considered as one group.) The web is fragmented like this due to several different reasons. First off it's because the development of search engines. More then half of the web is not detected or linked by a search engine. The world wide web is a scale-free network, dominated by hubs and nodes with a very large number of links? (Barabasi, 2001)
The hubs are essentially the central core. There are links going out from the central core to the OUT continent; however, there might not be a link going back to the central core from OUT. Links go into the central core from IN, just like the OUT continent, there might not be a way to go out to the IN continent from the central core. Between IN and OUT there is a tube that connects the two continents. Tendrils are extended from the IN and the OUT continent like a tumor because they are not reachable by the central core but they are reachable by the IN and OUT continents. Basically those are what we see as the web. HOWEVER, we have to look at the islands. Islands are the web documents that we don't usually find because it's not linked to anything and nothing is linked to it. It's isolated. Unless those documents submit their links to the search engine themselves, it becomes pretty hard for us to reach to them. Once we get into the island, we have no way out either because we cannot link to other places.
The continents of web illustrate the idea of directed network entirely because we can see that usually there's no reverse path from one link to another.
Wouldn't mapping out the whole internet (including the islands), gives us an opportunity to fly from continent to continent?
