And finally, the other really important bucket is authority. Google wants to show sites that are popular. If they can show the most popular t-shirt seller to people looking to buy t-shirts online, that’s the site they want to show. So you have to convince Google - send them signals that your site is the most popular site for the kind of t-shirts that you sell.
Robots.txt is not an appropriate or effective way of blocking sensitive or confidential material. It only instructs well-behaved crawlers that the pages are not for them, but it does not prevent your server from delivering those pages to a browser that requests them. One reason is that search engines could still reference the URLs you block (showing just the URL, no title or snippet) if there happen to be links to those URLs somewhere on the Internet (like referrer logs). Also, non-compliant or rogue search engines that don't acknowledge the Robots Exclusion Standard could disobey the instructions of your robots.txt. Finally, a curious user could examine the directories or subdirectories in your robots.txt file and guess the URL of the content that you don't want seen.
Mobile-first design has been a best practice for a while, and Google is finally about to support it with mobile-first indexing. Learn how mobile-first indexing will give digital marketers their first real swing at influencing Google’s new AI (Artificial Intelligence) landscape. Marketers who embrace an accurate understanding of mobile-first indexing could see a huge first-mover advantage, similar to the early days of the web, and we all need to be prepared.