In the past, Chrome indicates HTTP-only connections with a neutral indicator, represented by an info icon.

HTTPS connections however, contain a lock icon and the word “Secure”. If you click for more information, you will be shown the site is classified as secure and that your information is private when it is sent to this site.

According to the Google Security Blog, the neutral indicator “doesn’t reflect the true lack of security for HTTP connections. When you load a website over HTTP, someone else on the network can look at or modify the site before it gets to you.”

As of the 31st January 2017, Google Chrome (Chrome 56) will make HTTP pages with password or credit card form fields as “not secure”.

Googles next step will be to have, Chrome label all HTTP pages regardless of content with a red triangle to warn users the the connection is unsecure.

Plus, with HTTPS becoming a more relevant search ranking factor, getting a SSL certificate has become a must for website owners in 2017.

What is SSL?

SSL (Secure Sockets Layer) is the standard security technology for establishing an encrypted link between a web server and a browser. This link ensures that all data passed between the web server and browsers remain private and integral. SSL is an industry standard and is used by millions of websites in the protection of their online transactions with their customers.

Source https://info.ssl.com

Google Recommendations on SSL can be found in this article:

http://support.google.com/webmasters/answer/6073543?hl=en