How Search Engines Work

Every time you search –Search Engines crawl millions of pages with helpful information. When users type a query in the search box, the search engines return with pages that have “most relevant” or “best” information.

Before the user searches, the search engines organize the information about the web pages in its ‘search index’. 

The web crawlers, also known as spiders or search bots, navigate by downloading the content on these pages and following the links on these pages to find new pages with relevant information.  

Let’s dig deeper to understand the mechanism i.e Crawl, Index and Rank the website.

Indexing

The webpages discovered by the search engines are added to a data structure known as ‘Index’.

It includes the crucial signals about the content of each URL such as – keywords, content, freshness, user-engagement etc.

Once a page is indexed, it is added to the queue of relevant queries.     

Crawling 

Crawling is the process in which search engines send a team of robots to find new, relevant and updated content. The content could be a web page, video, image or PDF – regardless of the format.  

The crawlers will find new and most relevant content by hopping the paths of links and add them to the ‘Caffeine’ - which is their massive database of URLs.

Crawling the entire website would take a lot of time. So, Google spreads the crawlers over several weeks. Instead of indexing every website, it starts indexing a trusted set of websites.  

Ranking

When a user performs a search, the search engines surface the index for highly relevant content and sequences it to solve the searcher’s query. The ordering of the results is known as “Ranking”.

Higher is the rank of the webpage, the more relevant the search engines believe that page is to the search query

If you want the content to be found on search engines, you need to make sure it is indexed and is accessible to the crawlers. There are several circumstances under which the webpage is not indexed by a search engine