In a few weeks all users who are signed into Google Account will use search solution over SSL certificate with protocol: https://www.google.com.
SSL certificate is rising on-line security. Now, even search terms and search results will be encrypted and secured from being intercepted by a third party. It is especially important when Internet access is offered by free hotspots, unknown providers etc.
Users who are not signed into a Google Account may also use the https:// protocol. It will not work automatically. The "s" has to be typed into the URL address.
Google uses Thawte SSL certificates. See details at Google Support.
If you run a online business, you are sure to use Google AdWords. Perhaps this is one of the main traffic sources on your site, so the last message you want to see is "Your account has been suspended ...". And yet, you can expect it if your site is not SSL-secured.
Starting 1st of August 2016, Comodo and DomenySSL will no longer offer SGC variants of certificates. As your account has a valid SGC certificate which will be up for renewal in the future, the company has prepared a list of recommended alternatives.
Thawte is only one of the few vendors outside of the United States. As the main competitor of American vendors quickly gained a 40 % share of the market SSL certificates.