Intermediate
Cryptography
TLS & HTTPS
The protocol that encrypts and authenticates your connection to a website.
In simple terms
The padlock means your traffic is encrypted and the server proved it owns the domain — nobody on the network can read or tamper with the pages you load.
Analogy
An armoured courier who also checks the sender's ID badge against a government registry before handing anything over.
Going deeper
TLS 1.3 handshakes combine an X.509 certificate chain check (asymmetric, for identity) with ephemeral X25519 key exchange (forward secrecy) and then switch to fast symmetric AEAD for the data. Fewer round trips than TLS 1.2 and no legacy cipher suites.
Common mistake
A valid certificate only proves the connection is encrypted to the right domain — phishing sites have padlocks too.