The Site Information panel is where you can view information about a website's connection security and identity.
A padlock icon in the address bar will indicate whether the connection to the website is fully secure. For more information, click the padlock to open the Site Information panel. This panel shows you whether the current connection is classified as secure.
Click the right arrow in the Site Information panel to view the Connection Security panel. This is where you can learn more about connection security, such as the issuer of a certificate for a secure connection and – if it is made available – the website's owner, or disable the blocking of insecure content on a site. This panel also includes a Page Info window tab for the website.button that will open the
See How do I tell if my connection to a website is secure? to learn more about connection security. The Mixed content blocking in Firefox article tells you about Firefox's content blocking security feature.