Google Search Console
Google Search Console (formerly Google Webmaster Tools) is a free analytics tool that reveals how a website works from a Google search engine. This service also reports possible search errors that may result in a loss of traffic to your site. For example, you can find out how and if Google searches for your site at all, the number of pages that are actually indexed, the number of impressions, and the clicks that lead to your site. Furthermore, this way you will discover defective and duplicate tags or shortcomings of the website in general. The Google Search Console also allows you to index new or modified pages faster, tells you through which images and through which keywords individual users came to you, etc.