How to check google indexing my site?

We have a website. Is a little old, some content. And want to know how Google sees. You must type in the Google search bar following code
site:domain.com
Exemple: we want to verifying site google.com, in order to see how many indexing has. So we write in the search box: site:google.com

If we want to verifying yahoo.com, we will write in search box: site:yahoo.com. If we want another site we will write site:sitename.com, or another extensiones of damain (.info, .net, .org, .name, ...).