how d search engines build their indexes and how the indexes are ultimately accessed by the user.
I went to www.google.com and entered how search engines work, and here are the results:
http://www.google.com/search?q=how+search+engines+work&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7SUNA
The first three or four have the best information.
=)
Search engines build their indexes by crawling the web and analyzing the content of websites. Here's a step-by-step explanation of how they do it:
1. Crawling: Search engines use automated programs called "crawlers" or "spiders" to visit web pages. These crawlers follow links on websites, making their way through different pages over time. They start from a known set of URLs, such as popular websites or web pages submitted by website owners.
2. Parsing: As the crawlers visit web pages, they download and analyze the HTML code of each page. They extract various elements like the page title, headings, text content, images, links, and meta tags.
3. Indexing: After parsing the web page, search engines create an index – a searchable database that contains information about the content of each web page. The index helps search engines quickly retrieve relevant results based on user queries. Indexing involves organizing the extracted information, such as keywords, into a structured format that can be efficiently searched.
4. Ranking: When a user inputs a query, search engines fetch relevant results from their indexes. To determine the order of search results, search engines employ algorithms that consider various factors like keyword relevance, website authority, user engagement, and other ranking signals.
5. Accessing the index: When a user conducts a search, their query is sent to the search engine's server. The server then retrieves the relevant results from the index based on the query. The search engine applies its ranking algorithms to determine the order of the results.
6. Displaying search results: The search engine presents the user with a list of relevant web pages, typically in a ranked order. Users can click on the search results to access the full web page.
In summary, search engines build their indexes by crawling the web, analyzing web page content, and creating a structured database. When a user searches, the search engine retrieves relevant results from the index based on the query and displays them in a ranked order.