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2026-04-14·5 min read

TLS vs SSL: What is the Difference and Why It Matters

TLS and SSL: the short answer

SSL (Secure Sockets Layer) is the predecessor to TLS (Transport Layer Security). SSL is obsolete and has known vulnerabilities. TLS is the modern, secure protocol that protects web traffic today.

When people say "SSL certificate" or "SSL encryption," they almost always mean TLS. The term SSL stuck around because of brand recognition, but every modern secure connection uses TLS.

A brief history

  • **SSL 1.0 (1994)** — never released due to security flaws
  • **SSL 2.0 (1995)** — first public release, quickly found vulnerable
  • **SSL 3.0 (1996)** — major rewrite, but broken by POODLE attack in 2014
  • **TLS 1.0 (1999)** — first TLS version, based on SSL 3.0
  • **TLS 1.1 (2006)** — minor improvements, now deprecated
  • **TLS 1.2 (2008)** — current widely-supported standard
  • **TLS 1.3 (2018)** — latest version, faster and more secure

    • Why the distinction matters

    Compliance requirements

    PCI-DSS, HIPAA, and other compliance frameworks require TLS 1.2 or higher. If your server still supports SSL 3.0 or TLS 1.0/1.1, you may fail compliance audits.

    Security vulnerabilities

    SSL 2.0, SSL 3.0, TLS 1.0, and TLS 1.1 all have known vulnerabilities:

  • **POODLE** — exploits SSL 3.0 to decrypt data
  • **BEAST** — attacks TLS 1.0 CBC ciphers
  • **CRIME/BREACH** — exploits TLS compression

    • TLS 1.2 and 1.3 are not affected by these attacks when configured correctly.

    Performance

    TLS 1.3 is significantly faster than older versions. The handshake completes in one round trip instead of two, reducing connection latency by 100ms or more. It also supports 0-RTT resumption for repeat visitors.

    What you should support

  • **TLS 1.3** — enable it everywhere (best security and performance)
  • **TLS 1.2** — keep for compatibility with older clients
  • **TLS 1.1 and below** — disable completely

    • How to check your TLS configuration

    Method 1: Use a free checker

    [CQwerty Shield's TLS Checker](/tools/tls-checker) tests your server and reports which TLS versions are supported, your cipher suites, and an overall grade.

    Method 2: Command line

    openssl s_client -connect example.com:443 -tls1_3

    Replace -tls1_3 with -tls1_2, -tls1_1, or -tls1 to test specific versions.

    Key takeaways

  • SSL is dead. TLS is the standard. Use TLS 1.2 and 1.3 only.
  • "SSL certificates" are really TLS certificates. The name is just legacy.
  • Disable TLS 1.1 and below on all servers.
  • TLS 1.3 is both faster and more secure than 1.2.
  • Test your configuration regularly, as server updates can re-enable old protocols.

    • [Check your TLS configuration now](/tools/tls-checker)

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