The spiders crawl the URLs systematically. Concurrently, they refer to the robots.txt file to check whether or not they are permitted to crawl any unique URL. After spiders complete crawling old pages and parsing their articles, they Look at if a web site has any new webpages and crawl them. https://trendsonseotoolscenters63949.blogrenanda.com/35728729/top-guidelines-of-explore-seotoolscenters