Malav Shukla

Google’s Query Processor

The query processor has several parts, including the user interface (search box); the “engine” that evaluates queries and matches them to relevant documents, and the results formatter.

Google considers over a hundred factors in determining which documents are most relevant to a query, including the popularity of the page, the position and size of the search terms within the page, and the

proximity of the search terms to one another on the page. PageRank is Google’s system for ranking web pages.

Google also applies machine-learning techniques to improve its performance automatically by learning relationships and associations within the stored data. For example, the spelling-correcting system uses such techniques to figure out likely alternative spellings

Indexing the full text of the web allows Google to go beyond simply matching single search terms. Google gives more priority to pages that have search terms near each other and in the same order as the query. Google can also match multi-word phrases and sentences. Since Google indexes HTML code in addition to the text on the page, users can restrict searches on the basis of where query words appear, e.g., in the title, in the URL, in the body, and in links to the page, options offered by the Advanced-Search page and search operators.