What Does a Search Engine Do?

Search engines have four main functions:

• They crawl the web (via spiders).

• They index the web documents and pages they find.

• Search engines process user queries.

• Finally, they return ranked results from the index.

A search engine is made up of a number of parts all working together:

• A crawling spider, also known as a web crawler, robot or bot, is an

automated indexing program. It goes from page to page, following

links and indexing or recording what it finds.

• The index is what the spider creates. It is a “library” of pages on the

Internet and it consists of tens of billions of pages! The search engine

creates databases for keywords, so it knows where to go to when a

user enters a query.

• The engine is the part that does the actual searching. Users input

a search query by typing a keyword or phrase into the search bar.

The engine then checks its index to find relevant pages and delivers

them ordered from most relevant and important to least relevant and

unimportant.

• The SERP (search engine results page) is the ordered listing of

results for the user’s query. A SERP contains a description and link

to the result.