A search engine works through three main stages: crawling, indexing, and
serving search results. 1. Crawling:
Search engines use automated software called web crawlers, bots, or spiders to
discover web pages across the internet. These crawlers visit websites, follow
links on pages, and download content such as text, images, and videos. The
crawling process is guided by rules like the robots.txt file, which can allow
or block access to certain pages. Crawlers continuously explore the web to
find new or updated content
. 2. Indexing:
After crawling, the search engine processes and analyzes the collected
content. It stores this information in a large database called the index. The
index contains details about each page, including keywords, content type,
freshness, and user engagement signals. This organization allows the search
engine to quickly retrieve relevant information when a user performs a search
. 3. Ranking and Serving Results:
When a user enters a query, the search engine searches its index for relevant
pages. It uses complex algorithms to rank these pages based on factors like
relevance to the query, quality of content, user intent, location, language,
device, and previous search history. The search engine then displays the most
pertinent results on the Search Engine Results Page (SERP)
. In summary, a search engine does not search the live web at query time but searches its pre-built index to deliver fast and relevant results. The process involves continuous crawling to discover content, indexing to organize it, and ranking algorithms to serve the best matches to users
. This system allows search engines like Google, Bing, and others to efficiently help users find information on the vast internet.
