Working of a Search Engine

Search engines especially Google Search has become an integral part of our lives. Be it professionally, where we need search engines to have answers for all our daily work queries or even personally where we search all sorts of different stuff. Since the advancement of the internet era, Search Engines has been the most powerful invention. It won’t be wrong to say that we are reliant on search engines. Have you ever wonder what goes behind the working of a search engine? How does search engine process within seconds and revert us with the required detail with just a mere click.

The working of search engine includes three main stages:

• Crawling
• Indexing
• Retrieval and Ranking

Crawling:

Crawling is the process by which search engine fetches and discovers content from all the available websites. Now the question arises who does the crawling? It’s the search engines’ software known as Google Boot or Spider which visits each website and gathers all the data available on it like title, description, keywords, images, links to other sites, alt tag and etc.
Any website that has been manually indexed or an already indexed website would be crawled. In addition to this, any site that is linked to the crawled site would be crawled next. So, this way the spider keeps scanning websites across the web to check if something new has been updated on the websites and also to discover content from the new websites.

Indexing:

Post crawling, we get the large chunk of data. These document retrieved from various websites are first merged into a single consistent format before they are indexed. A software known as ‘document processor’ processes this data and performs stemming on it which removes the word suffixes and also deletes the stop words like articles (a,the ), conjunction(and, but), preposition(in, over) and verb(is, are). This reduces the text size and hence consumes less space while indexing.

An index is a sort of inverted file which stores each word in the document and also saves pointers where that word appears in the document. This enormous volume of data is stored in large data centers which usually have more than 100 million gigabytes of data. When the users enter the search query on the search engine the relevant documents are fetched from the index and returned to the user.

Retrieval and Ranking:

The last stage is where user types search query while interacting with the search engine. The search engine does two things, Firstly, it retrieves the relevant information and web pages from index and secondly, it ranks those web pages and shows the best-ranked page on the top of search result. For accurate retrieval and ranking search engines uses various algorithms which keep changes with time. The ranking algorithm checks various parameters to decide the page rank. Content quality, freshness of content, relevance, keyword used, page layout, images and around 200 other factors are taken into consideration before deciding the page rank. So there is no hit formula which can guarantee you a higher page rank but there are some good practices which if followed can certainly improve the page rank. Some of them write quality content, use relevant keywords, more relevant sub-links, more links on other websites pointing to your content.

So this precisely sums up the working of the search engine in brief.