What is TLS/SSL?

When we use HTTPS to communicate with a web server, we use asymmetric encryption. For asymmetric encryption, we would need a public key, and a private key. The authenticity of the public key is unknown which is where SSL certificate comes to play.

SSL certificate is a signed certificate by a CA which is trusted. The CA uses their private key to sign the certificate which includes to whom the certificate is issued to, the validation period, and the public key. Since the public key is attached with the certificate, it proves the legitimacy of the public key that will be used for further secure communication between the webserver and the client.

Source 1: www.cloudflare.com

When SSL version 3.0 was being updated, instead of it being called SSLv4.0 it was renamed to be TLSv1.0.

The latest standard version is TLSv1.2.