Clustering
Clustering just means grouping. Grouping results makes them easier to read or follow. Many search engines use site clustering, including Google. When it finds more than one result that are on the same website, it shows the second result indented from the first, and hides the rest, so the results aren’t filled with listings from a single website. Since most websites are generally about one topic, site clustering is one step towards topic clustering. Topic Clustering, or grouping results into topics/subjects, are a good tool to help refine searches.
Directories are edited and organized by humans, and all websites are listed in a hierarchy, grouped according to their topic, and sub topics are listed within topics. Search engines’ databases have no such structure, which would help to focus in on a topic. Many words and phrases have multiple meanings, and this is not a problem for directories, but it is for search engines. For example ‘apple’ is a fruit but also happens to be the name of a small computer company. To solve this problem, many search engines are enhanced by also using a directory. For example, a search for ‘apple’ on Google will have two categories listed, apple - the fruit and Apple - the computer company. However, when you browse these categories, you are just using a directory and have lost the benefits of a search engine. The solution to all this, is topic clustering.
