When Firefox loads a web page, it indicates whether the connection is safe by the icon on the left of the address bar, the secure sign on the HTTPS website, and the HTTP web site does not have a visually obvious warning sign “Not Secure”. Mozilla plans to change the way in the future: its current release of Firefox Nightly Edition (v59) includes a confidential configuration option that will reveal obvious links to unsafe warning signs to HTTP sites when activated.
Reference: bleepingcomputer
