Web sites are found by their addresses on the World Wide Web. These addresses are known as URLs, or Uniform Resource Locators. Every website has a URL assigned to it, so both searchers and Web servers can find them quickly and easily.
Cluster analysis or clustering is the task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some sense or another) to each other than to those in other groups (clusters).
Clustering, or concept mapping, is when you write down a very broad topic or idea and then make a concept map, in which you diagram smaller ideas or categories that go into the central topic. The goal of clustering, much like freewriting, is to come up with lots of different possibilities.