Transport Layer Security (TLS)

Transport Layer Security (TLS) is a protocol that protects network communication with encryption, integrity checks, and authentication.

Format
Security & Encryption
Updated
Updated
Glossary Security & Encryption
Transport Layer Security Also known as TLS.Aliases: SSL, TLS protocol, secure transport.

Definition

Transport Layer Security (TLS) is a protocol that protects network communication with encryption, integrity checks, and authentication.

How it works

A TLS session starts with a handshake: the endpoints agree on cryptographic parameters and the client checks the server's certificate against its trust store. From then on, application traffic — HTTP, mail, and more — is encrypted and tamper-evident in transit. TLS 1.3, the current version, trimmed the handshake and dropped the weak options of earlier eras.

Example: HTTPS uses TLS to protect communication between a browser and a web server.

Often confused: SSL was TLS's predecessor, deprecated long ago — the name lives on in "SSL certificate", but the protocol on the wire is TLS.

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Last reviewed 2026-07-19.