What is the difference between SSL and TLS?

SSL and TLS are the technology that encrypts the connection between a visitor’s browser and your website — the padlock and the “s” in “https”:

• TLS is the modern version, SSL its obsolete predecessor — SSL was retired years ago for being insecure, and every encrypted connection today actually uses TLS.
• The name just stuck around — “SSL” lingered in everyday language and product names, which is why an “SSL certificate” is really a TLS certificate.
• What actually matters is the version in use — TLS 1.2 and TLS 1.3 are current and safe, while TLS 1.0 and 1.1 are deprecated and will earn a downgraded grade from a checker like SSL Labs.

Ignore the SSL-versus-TLS wording; the only question that matters is whether your server runs TLS 1.2 or 1.3 and has dropped the older versions.