You may not want certain pages of your site crawled because they might not be useful to users if found in a search engine's search results. If you do want to prevent search engines from crawling your pages, Google Search Console has a friendly robots.txt generator to help you create this file. Note that if your site uses subdomains and you wish to have certain pages not crawled on a particular subdomain, you'll have to create a separate robots.txt file for that subdomain. For more information on robots.txt, we suggest this Webmaster Help Center guide on using robots.txt files13.
Display advertising - As the term infers, Online Display Advertisement deals with showcasing promotional messages or ideas to the consumer on the internet. This includes a wide range of advertisements like advertising blogs, networks, interstitial ads, contextual data, ads on the search engines, classified or dynamic advertisement etc. The method can target specific audience tuning in from different types of locals to view a particular advertisement, the variations can be found as the most productive element of this method.