Chapter 2, Who, What, Where, Why, When, and How (Much) Summary

Most search engines work by taking the keywords entered by the user, creating a database query from the keywords and returning a list of URLs that includes a summary of content for each URL. Components of a search engine include a crawler that sends information requests out on the Internet and collects information from Web sites, an index created from the information gathered by the crawler and a user interface to construct the database queries and to return the results. This basic model has remained largely unchanged since the 1970s.

Search results are termed SERPs (Search Engine Result Pages). Just how relevant the SERPs are to a user's keywords depends on how often the crawler visits and revisits Web pages and how much information the crawler gathers...