{Till some time back|Till few years back" no one bothered if your website was using SSL or not. Infact the term was not known to many and very few knew about the trusted seals offered by security companies. If your website was on HTTPS you were considered to be someone who was overly cautious about client security.
Things changed as Google released an update to Chrome more info in Feb 2018
Google Chrome and all the leading browsers like Safari, Firefox, Edge etc started tagging websites which were not on HTTPS as insecure.
How you can ensure that you are not running an insecure website?