Glossary · Definition
SSL
SSL (Secure Sockets Layer) is the obsolete encryption protocol that became TLS in 1999. The term stuck culturally — 'SSL certificate' actually means a TLS certificate today — but every secure connection on the modern web is TLS, not SSL.
Definition
SSL (Secure Sockets Layer) is the obsolete encryption protocol that became TLS in 1999. The term stuck culturally — 'SSL certificate' actually means a TLS certificate today — but every secure connection on the modern web is TLS, not SSL.
What it means
SSL was developed at Netscape in the mid-1990s. SSL 1.0 was never released, 2.0 had serious flaws, 3.0 (1996) was the dominant version until TLS 1.0 superseded it in 1999. Both SSL 2.0 and 3.0 have been formally deprecated by the IETF (2011 and 2015 respectively, after the POODLE attack proved SSL 3.0 was insecure). Despite this, 'SSL' remains the marketing term for HTTPS — Certificate Authorities sell 'SSL certificates' that are actually TLS certificates, and admins talk about 'SSL termination' to mean TLS termination.
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Why it matters
Anywhere you see 'SSL' in 2026 it should be read as 'TLS'. If you see a configuration that actually enables SSL 2.0 or 3.0 — disable it. Modern config: TLS 1.2 + 1.3 only, no SSL versions, ECDHE cipher suites with AES-GCM or ChaCha20-Poly1305, HSTS header set. SSL Labs (Qualys) gives every public HTTPS site a letter grade — A or A+ is achievable with default configs from Let's Encrypt + a reasonable nginx/Caddy/Vercel setup.
Frequently asked questions
Should I worry if I'm still using SSL?
Yes. SSL 2.0 and 3.0 are broken. If your server config explicitly mentions SSL, audit the cipher suite list and disable everything pre-TLS 1.2.
Why is the term still everywhere?
Inertia. 'SSL certificate' is what cert vendors trained the market to say. 'SSL termination' is what load-balancer docs called the feature. Renaming everything to TLS would be technically correct but commercially inconvenient.
Related terms
- DefinitionTLSTLS (Transport Layer Security) is the encryption protocol that wraps any TCP connection in an authenticated, encrypted tunnel. It's what makes HTTPS, secure SMTP, and most modern internet traffic private.
- DefinitionHTTPSHTTPS is HTTP wrapped in a TLS-encrypted tunnel. Everything between your browser and the server — URLs, form data, cookies, response bodies — is encrypted in transit so a network observer (cafe Wi-Fi, ISP, anyone in between) can't read it or change it.