# HTTPS and TLS Basics

> What HTTPS guarantees, how certificates and the TLS 1.3 handshake work, and how to read a certificate and diagnose the errors customers report.

Canonical: https://codelivly.com/rooms/https-and-tls-basics
Last updated: 2026-11-15

| | |
|---|---|
| Level | Beginner |
| Category | Web |
| Lessons | 6 |
| Estimated time | 3 h 30 min |
| XP | 150 |

HTTPS is HTTP inside a TLS connection, and this room takes that connection apart. You learn what TLS protects on a shared network and what it leaves visible, how keys, certificates and certificate authorities fit together, and what each message of the TLS 1.3 handshake does. You then read a certificate field by field, work out days to expiry from the terminal, and tell an expired certificate from a name mismatch, a missing intermediate, a wrong clock and mixed content. The room ends with a guided lab in which you build a certificate inventory for five Fernhill hosts.

## Lessons

1. What HTTPS Protects and What It Does Not (30 min)
2. Keys, Certificates and Certificate Authorities (30 min)
3. The TLS 1.3 Handshake Step by Step (35 min)
4. Reading a Certificate: Names, Dates and the Chain (35 min)
5. When HTTPS Goes Wrong: Warnings, Expiry and Mixed Content (35 min)
6. Guided Lab: Check the Certificates of Five Sites (45 min)

## Related

- [Learning path: Web Fundamentals](https://codelivly.com/learning-paths/web-fundamentals)
- [All rooms](https://codelivly.com/rooms)