For a website to apply SSL/TLS encryption it must have an SSL certificate. The certificate, which is stored on the webserver, acts as an ID card to prove that the website is genuine and not fake.

SSL/TLS certificates store the website’s unique ID referred to as a public key. The public key is used by a website visitor’s device to establish a secure connection with the webserver.

The SSL Labs project was created in 2009 and their goal was to provide diagnostics for identifying security concerns in computer configurations. SSL Labs created an alphabetical grading system for SSL / TLS certificates. The grades rate secure configuration out of 100. These are alphabetical grades, which range from F to A+, and are a way of measuring security configuration quality.

An A+ SSL grade is given when the server configuration is determined to be exceptional.