When people talk about secure data transmission, the terms SSL and TLS usually come up. The padlock in the address bar, addresses starting with https://, banking and e-commerce sites — the technology working behind all of them is, more often than not, TLS. So what is TLS, how does it differ from SSL, and why do we still say "SSL"?
What Is TLS?
TLS (Transport Layer Security) is a protocol that secures data transmission across the internet by encrypting it. The data between browser and server is encrypted by TLS, its integrity is preserved, and it can't be read by unauthorized parties. It has three core jobs:
- 🔒 Confidentiality — encrypts data so third parties can't read it.
- 🛡️ Integrity — guarantees the data wasn't changed in transit.
- ✅ Authentication — verifies that the server you connect to really is the right one.
What Is SSL?
SSL (Secure Sockets Layer) is considered the ancestor of TLS. It was developed by Netscape in the mid-1990s and became the standard for secure data transmission on the internet. But because of security weaknesses and technical advances, it gave way to the TLS protocols. Today, even though browsers and servers use the name "SSL," most connections technically run over TLS.
Why Do We Still Use the Term "SSL"?
Almost all the HTTPS connections we use today run on TLS 1.2 or TLS 1.3. The document we call an "SSL certificate" is really a TLS certificate. But the word "SSL" is so entrenched in the industry that marketing and technical documents still use the phrase "SSL certificate."
The Key Differences Between SSL and TLS
| Criterion | SSL | TLS |
|---|---|---|
| Era | 1990s (Netscape) | First release in 1999; current is TLS 1.3 |
| Security | Older, with known weaknesses | Stronger algorithms, improved security |
| Performance | Slower handshake | Connects faster |
| Support | Not supported in modern browsers | The only supported protocol |
What Does "256-bit" Mean?
You'll see "256-bit" on many TLS/SSL certificates. It refers to the length of the symmetric key used to encrypt session data. 256-bit encryption is provided by the AES (Advanced Encryption Standard) algorithm, and the number of possible combinations is astronomical (2^256). Even today's most powerful supercomputers would, in practice, need billions of years to brute-force it — which makes it one of the strongest standards in use today.
Why TLS Matters Today
As of 2025, TLS 1.3 is regarded as the internet's most secure and fastest encryption protocol. What stands out:
- 🤝 Fast handshake — it reduces the steps in the "handshake" when a connection is set up. The handshake is the process where browser and server mutually agree on encryption settings and keys; fewer steps mean pages load faster.
- 🛡️ Strong encryption — more robust encryption algorithms.
- 🔏 Extra privacy — additional security features that improve privacy.
Banking, e-commerce, and any site handling sensitive data must use TLS.
Its Relationship With HTTPS and SEO
HTTPS is the version of HTTP secured with TLS (formerly SSL); for it to work, there's always a TLS certificate behind the scenes. The padlock and the https:// prefix in the address bar show that data is encrypted and a secure connection has been established.
Google has given a ranking advantage to sites using HTTPS (and therefore TLS) since 2014. On top of that, browsers like Chrome flag sites that don't use HTTPS as "Not Secure" — something that directly affects visitor trust.
What we call an "SSL certificate" today is really a TLS certificate.
Summary
- TLS is the modern, more secure version of SSL.
- What's called an "SSL certificate" today is really a TLS certificate.
- TLS 1.3 is the best option for speed and security.
- 256-bit encryption is one of the highest levels of internet security.
- HTTPS doesn't work without TLS; it's essential for both SEO and user trust.