Google Search Console (Webmaster Tools)

Do you want to know how Google sees your website?

Start using Google Search Console (formerly Webmaster Tools). It is a comprehensive set of tools that you can use to improve your search rankings. It can help you find out which keywords from your site are ranking higher, which keywords are clicked more often, and more.

You can submit XML sitemap to Google which will help Google discover and crawl your site better.

Most importantly, Google will notify you when there are problems crawling or indexing content from your site. Google will also show you errors and warnings with suggestions on how to resolve them.

This immense wealth of information is a must-have for all website admins.