What is TLS / SSL?

TLS (Transport Layer Security), the successor to SSL, is the cryptographic protocol that encrypts data between a client and server. It is what turns HTTP into HTTPS, protecting traffic from eavesdropping and tampering.

TLS uses certificates to prove a server’s identity and to establish an encrypted session. "SSL" is the older name still used loosely, but modern connections use TLS.

Key points

  • Encrypts data in transit between client and server.
  • Turns HTTP into HTTPS (default port 443).
  • Uses certificates to verify a server’s identity.
  • "SSL" is the legacy name; TLS is what is actually used today.

Example

https://example.com   ← TLS-encrypted
http://example.com    ← plaintext

Common uses

  • Securing all production web traffic (HTTPS)
  • Encrypting API calls and form submissions
  • Protecting logins and sensitive data
  • Meeting security and SEO requirements

More terms