How The Search Engine Works?

Search Engine refers to a huge database of internet resources such as webpages, newsgroups, programs, images etc. It helps to locate information on World Wide Web.


 It is also known as spider or Googlebots. It is a software component that traverses the web to gather information.

Search Engine Working

Webcrawler, database and the search interface are the major component of a search engine that actually makes search engine to work. Search engines make use of Boolean expression AND, OR, NOT to restrict and widen the results of a search. Following are the steps that are performed by the search engine:

The search engine looks for the keyword in the index for predefined database instead of going directly to the web to search for the keyword.

It then uses software to search for the information in the database. This software component is known as webcrawler.

Once web crawler finds the pages, the search engine then shows the relevant webpages as a result. These retrieved webpages generally include title of page, size of text portion, first several sentences etc.

These search criteria may vary from one search engine to the other .The retrieved information is ranked according to various factors such as frequency of keywords, relevancy of information, links etc.

A crawler is a program that naturally looks through reports on the Web. Crawlers are fundamentally customized for monotonous activities with the goal that browsing is automated. Search engines use crawlers most frequently to peruse the web and build an index. Different crawlers search various kinds of data, for example, RSS channels and email addresses. The term crawler originates from the main search engines on the Internet: the Web Crawler. Synonyms are likewise "Bot" or "spider." The most known webcrawler is the Googlebot.

Search engines are the door of simple access data; however web crawlers, their little-known sidekicks, assume a pivotal job in gathering together online content. In addition, they are fundamental to your search engine optimization (SEO) strategy.

The crawling process begins with a list of web addresses from past crawls and sitemaps provided by website owners. As our crawlers visit these websites, they use links on those sites to discover other pages. The software pays special attention to new sites, changes to existing sites and dead links. Computer programs determine which sites to crawl, how often and how many pages to fetch from each site.

We offer Search Console to give site owners granular choices about how Google crawls their site: they can provide detailed instructions about how to process pages on their sites can request a recrawl or can opt out of crawling altogether using a file called “robots.txt”. Google never accepts payment to crawl a site more frequently — we provide the same tools to all websites to ensure the best possible results for our users.

Finding information by crawling

The web is like an ever-growing library with billions of books and no central filing system. We use software known as web crawlers to discover publicly available webpages. Crawlers look at webpages and follow links on those pages, much like you would if you were browsing content on the web. They go from link to link and bring data about those webpages back to Google’s servers.

Organizing information by indexing

When crawlers find a webpage, our systems render the content of the page, just as a browser does. We take note of key signals — from keywords to website freshness — and we keep track of it all in the Search index.

The Google Search index contains hundreds of billions of webpages and is well over 100,000,000 gigabytes in size. It’s like the index in the back of a book — with an entry for every word seen on every webpage we index. When we index a webpage, we add it to the entries for all of the words it contains.

With the Knowledge Graph, we’re continuing to go beyond keyword matching to better understand the people, places and things you care about. To do this, we not only organize information about webpages but other types of information too. Today, Google Search can help you search text from millions of books from major libraries, find travel times from your local public transit agency, or help you navigate data from public sources like the World Bank.

Examples of a crawler

The most well-known crawler is the Googlebot, and there are many additional examples as search engines generally use their own web crawlers. For example

·         Bingbot

·         Slurp Bot

·         DuckDuckBot

·         Baiduspider

·         Yandex Bot

·         Sogou Spider

·         Exabot

·         Alexa Crawler

How do web crawlers affect SEO?

SEO stands for search engine optimization, and it is the discipline of readying content for search indexing so that a website shows up higher in search engine results.

If spider bots don't crawl a website, then it can't be indexed, and it won't show up in search results. For this reason, if a website owner wants to get organic traffic from search results, it is very important that they don't block web crawler bots.

Significance for search engine optimization

Web crawlers like Googlebot achieve their purpose of ranking websites in the SERP through crawling and indexing. They follow permanent links in the WWW and on websites. Per the website, every crawler has a limited timeframe and budget available. Website owners can utilize the crawl budget of the Googlebot more effectively by optimizing the website structure such as navigation. URLs deemed more important due to a high number of sessions and trustworthy incoming links are usually crawled more often. There are certain measures for controlling crawlers like the Googlebot such as the robots.txt, which can provide concrete instructions not to crawl certain areas of a website, and the XML sitemap. This is stored in the Google Search Console, and provides a clear overview of the structure of a website, making it clear which areas should be crawled and indexed.