Chrome 56 (released January 2017) started labeling HTTP pages with input fields such as password or credit card form fields as “Not Secure”. Since then, Google’s stance on SSL adoption has progressed to the point where they now strongly enforce HTTPS across all websites.
Any websites not (properly) utilizing HTTPS/SSL will display clear “Not Secure” and “Your connection is not private” warnings when attempting to visit them.
There are less and less arguments to keep your site on the insecure HTTP protocol. Fortunately, switching to HTTPS became much easier over the years, with many hosting providers offering easy-to-implement solutions. You can also generate a Free SSL certificate for your website with the Really Simple SSL plugin.