SSL and TLS : What's the Difference?

The terms SSL and TLS are used almost interchangeably, so the difference between them is easy to miss. They are closely related but not the same, and understanding how they connect explains something that puzzles many people : why the file you buy is called an SSL Certificate when the technology securing your website is actually TLS.

This article explains what each one is, how one replaced the other, and what that means for the SSL Certificate protecting your site.

Understanding Both Protocols

Secure Sockets Layer (SSL) and Transport Layer Security (TLS) are both cryptographic protocols. Each one encrypts the connection between a visitor's browser and your web server, so that anything passing between them cannot be read or altered along the way.

SSL came first, developed by Netscape in the mid 1990s. TLS is its successor, and every current secure connection uses TLS rather than SSL. The name SSL simply never left everyday use. Learn About The Terms Explained 🔗

Replacing SSL With TLS

SSL went through several versions during the 1990s, but weaknesses were found in each, and the protocol was eventually retired. TLS took its place, first as TLS 1.0 and then through to the current TLS 1.2 and TLS 1.3.

Every version of SSL, along with the earliest versions of TLS, is now considered insecure and is switched off on modern servers. A secure website today negotiates TLS 1.2 or 1.3, and nothing older. Learn About The Move to TLS 1.3 🔗

Same File, Different Name

This is the part that trips people up. An SSL Certificate enables an encrypted connection, and it is the same kind of file whichever protocol is in use. It was called an SSL Certificate when SSL was the standard, and the name stayed even as the protocol beneath it became TLS.

So an SSL Certificate and a TLS certificate are the same thing. The SSL Certificate you hold already works with modern TLS, and there is nothing on the SSL Certificate itself to replace when a newer version of TLS arrives. The SSL Certificate proves who you are, and the protocol does the encrypting.

What Changes Between TLS Versions

Each version of TLS improves on the one before. Older protocols relied on aging algorithms such as MD5 and SHA-1, while modern TLS uses stronger ones, including the Advanced Encryption Standard (AES) and Elliptic Curve Cryptography (ECC).

Modern TLS also provides forward secrecy, so that if a single session key were ever exposed, earlier sessions would stay protected. TLS 1.3 goes further again, removing older options altogether and completing the opening handshake more quickly. Compare Hashing and Encryption 🔗

Where Configuration Matters

Because your SSL Certificate already supports modern TLS, the place the difference matters is your server configuration rather than the SSL Certificate itself. A server can still be set to allow old, insecure protocols, which weakens security even with a current SSL Certificate installed.

The practical step is to make sure your server offers TLS 1.2 and 1.3, with SSL and the earliest TLS versions switched off. That configuration, together with a valid SSL Certificate, is what gives every visitor a secure connection. Learn About Installing an SSL Certificate 🔗

Your SSL Certificate Today

When you order an SSL Certificate, you are buying the file that enables encrypted TLS connections for your domain. The wording says SSL because that is the name people recognize, while the protection it provides is entirely modern.

Trustico® offers SSL Certificates at Domain Validation (DV), Organization Validation (OV), and Extended Validation (EV) levels, for single sites, wildcards, and multiple domains, all of which secure connections with current TLS. For hands-off management, the same protection is available through Certificate as a Service (CaaS). Explore Certificate as a Service (CaaS) 🔗

In short, SSL and TLS are two generations of the same idea. TLS is what secures your website now, the SSL Certificate is what makes it possible, and the only thing still carrying the older name is the name itself.