Full Text Retrieval and Search Engines

Every Web surfer knows that you only tackle the unstructured information flooding in the World Wide Web with the help of search engines. There are millions of Web pages on thousands of servers. Some page somewhere surely contains the needed information — but which one is it? Web search engines read a high percentage of all available pages, and use the contents to build a database of words, a so-called full text index. Using this index, particular terms can be located quickly. Depending on the indexing and query software, complex queries — such as queries involving Boolean operators (and, or, not) for combining multiple terms — may be used.