End-to-End Encryption
Also known as: e2ee
Encryption where only the sender and recipient can read the message — not the service provider in the middle.
In end-to-end encryption, keys live on the endpoints (your phone, your laptop) and the server relays ciphertext it cannot decrypt. Signal, WhatsApp messages, iMessage and Apple's Advanced Data Protection all use E2EE.
E2EE protects content but not metadata: who talked to whom, when, and from where can still be logged. It's also incompatible with server-side content moderation, which is why regulators periodically propose weakening it.