{Till some time back|Till few years back" no one bothered if your website was running on HTTP or HTTPS. 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.
This all changed with a Feb 2018 when Google came out website with a update for Google Chrome and on its search engine prefering ranking to websites that were protecting their clients via HTTPS.
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?