What is End-to-End Encryption?

End-to-end encryption (E2EE) scrambles messages on the sender's device and unscrambles them only on the recipient's — the service in the middle carries them but cannot read them, even under legal demand.

WhatsApp, Signal and iMessage (blue bubbles) use it by default; some apps hide it behind a "secret chat" mode. Remember the caveat: backups may not be E2EE unless you enable encrypted backup separately.