When you request "example.com" from the location bar, Firefox will attempt to load
http://example.com over an insecure connection by default. Those who want to load the site over a secure connection have to manually put "https://" in front of the URL. Because it is easier to not type "https://", most websites are accessed over an insecure connection.
After installing this add-on, websites will be requested over https. You have to explicitly type "http://" to get the insecure version of the website. As of version 0.4, navigations from the location bar will always use HTTPS (except for localhost, IP addresses and dotless domains). Visit the preference page to add an exception if you don't want to use HTTPS by default for a specific site.
Firefox removes the "http://" prefix by default in the location bar. If you click on the location bar and press Enter, then you will request the https version of the website if you are currently viewing a http-website. If you want to preserve http, either put "http://" in front of the URL, or visit
about:config and set
false to prevent the "http://" prefix from being stripped in the first place.
This add-on is part of the HTTPS by default project, at https://github.com/Rob--W/https-by-default.