Spiders or Crawlers: Spiders are the software program triggered by the search engine to find new information and download a copy to the local database. It is initiated by a search engine to find new data on the internet.
In Simple words, we can also say a spider program is called as Web crawlers because they ‘crawl’ over the Web, to get a new or updated web page and collects documents to build a searchable index database for the search engines. The program starts at a website and follows every hyperlink on each page. Google’s web crawler is known as GoogleBot.
Whenever the spider finds a new data or webpage, it indexes (e.g give some number like an identity) that page so that it can use it use it in future. If any page is not indexed, it will not appear in search result.
How Search engine works:
- The search engine uses a spider, which is continuously crawling to find new and updated content on the web.
- Spiders stores a copy of all the information in the search engine database.
- The data stored in database is indexed according to its content.
- Whenever we search anything, the search engine checks the database for the relevant webpage, a relevant webpage means the webpage that has the content that we have searched.
- After getting all relevant webpages, search engine ranks the webpage according to its algorithm and shows it to the user.
Search Engine algorithm, plays a major role in determining the rank of the webpage. So it is very important for SEO and paid search advertiser to understand search algorithm.