In the Google Webmaster Tools, there is a Google Index Status section. I understand that, but what is the grey vertical line that marks an update? What gets updated there or, then?
...I just found the answer on: http://searchengineland.com/google-webmaster-tools-index-status-showing-data-https-protocol-187992 This is the explanation: "If you mix and match HTTP and HTTPS content on different pages, you will notice a change in your Index Status reports. Google has added an “Update” annotation to the report to convey when they started collecting and reporting on the HTTPS/HTTP data. The update annotation would show on March 9th, says Google."