SSL and TLS are closely related, but they are not the same thing. SSL is the original protocol that introduced encrypted web communication, while TLS is its modern, secure successor. Today, all secure internet traffic uses TLS, yet the term “SSL” is still widely used for historical and practical reasons.
SSL, or Secure Sockets Layer, was developed in the mid-1990s to protect data sent between browsers and servers. Early versions of SSL had serious security flaws, and although SSL 3.0 was widely adopted, it was eventually found to be vulnerable to modern attacks. As a result, SSL has been completely deprecated and disabled in all modern browsers and servers.
TLS, or Transport Layer Security, replaced SSL starting in 1999. It was designed to be more secure, more flexible, and formally standardized. While early TLS versions were very similar to SSL 3.0, later versions introduced stronger cryptography, better authentication, and improved resistance to attacks. Today, TLS 1.2 and TLS 1.3 are the only recommended versions, with TLS 1.3 offering better performance and security by removing outdated features entirely.
Despite SSL being obsolete, the term “SSL” remains in everyday use. This is mainly due to legacy terminology. For many years, SSL was the only name people associated with encrypted web connections, and the term became deeply embedded in documentation, product names, and industry language. When TLS replaced SSL, the public-facing terminology never fully caught up.
Another reason is simplicity and familiarity. “SSL certificate” is shorter, more recognizable, and easier to market than “TLS certificate,” even though both refer to the same type of X.509 certificate. Hosting providers, certificate authorities, and control panels continue to use “SSL” as a catch-all term to avoid confusing non-technical users.
There is also backward compatibility in naming, though not in protocol use. Certificates issued today work with TLS, but historically they were introduced as SSL certificates, and the naming convention persisted even as the underlying technology changed.
In short, SSL is a deprecated protocol that should never be used, while TLS is the modern standard securing the internet. We still say “SSL” because the term survived the technology itself. In practice, when someone talks about an SSL certificate or SSL encryption today, they almost always mean TLS-protected communication.