Links and the corresponding anchor text in web pages can readily be identified
and extracted during document parsing. Extraction means that this information
is recorded in the document data store, and can be indexed separately from the
general text content. Web search engines make extensive use of this information
through link analysis algorithms such as PageRank (Brin & Page, 1998). Link
analysis provides the search engine with a rating of the popularity, and to some
extent, the authority of a page (in other words, how important it is). Anchor text,
which is the clickable text of a web link, can be used to enhance the text content
of a page that the link points to. These two factors can significantly improve the
effectiveness of web search for some types of queries.