What is TLS?

Learn the fundamentals of Transport Layer Security and how it protects your data in transit.

What it is

Transport Layer Security (TLS) is a cryptographic protocol designed to provide secure communication over a computer network. It's the successor to SSL (Secure Sockets Layer) and is widely used to secure web traffic, email, and other network communications.

TLS operates at the transport layer of the OSI model, sitting between the application layer (HTTP, SMTP, etc.) and the network layer (TCP/IP). When you see "https://" in your browser, you're using TLS to encrypt the connection between your browser and the web server.

Why it matters

TLS provides three critical security properties:

Confidentiality: Data is encrypted so that only the intended recipient can read it.
Integrity: Data cannot be modified in transit without detection.
Authentication: The server (and optionally the client) can verify each other's identity using certificates.

Without TLS, anyone on the network path between you and the server could intercept, read, or modify your data. This is especially critical for sensitive information like passwords, credit card numbers, and personal data.

In practice

Best practices for TLS deployment:

Use TLS 1.2 or TLS 1.3 (avoid older versions like TLS 1.0 and 1.1)
Keep certificates up to date and monitor expiration dates
Use strong cipher suites and disable weak ones
Enable HSTS (HTTP Strict Transport Security) to force HTTPS
Regularly audit your TLS configuration for vulnerabilities
Use certificate pinning for high-security applications
Monitor certificate expiration and set up automated renewal

What is TLS?

What it is

Why it matters

In practice

Further reading