The crawler is also known as a program which pays a visit to the websites, plus reads their pages and other information with the intention of creating entries and rankings in the index page of say, Google. The bigger search engines are having a program, even known as a spider or a bot; crawlers are typically programmed to stopover to the websites, which are submitted by the owners as fresh or modernized. A crawler seemingly makes the most out of the name until it crawls through a site page at the time, following the links to the other site pages until all the pages have been read by it.
The term crawling literally means going through or scanning any kind of text and it could be links redirected for the other websites, captions for a picture, descriptions, articles, or any kind of content. The reason it is called spider is because the way spider extends its four limbs and walks over each and everything with the intent of covering everything, same is done by this bot program of google which you cannot under-estimate. Now search engines are bound to be the web crawlers with the added functionality of being capable of organizing them amassed websites in the lessening method of application. Every website owner uses a file known as ‘robots.txt’ to provide intimation and information to the crawler, as what page or website does it want to index and what page and website it doesn’t have to. There have been a number of modern crawlers which help you find a bug on a certain page or a website, plus you would be able to fix those issues as soon as possible, owing to the latest innovation. The main characteristics of these kinds of bots are that – they tend to perform much quickly than the other programs.