End-to-end encryption (E2EE) means a message is encrypted on your device and only decrypted on the recipient's — no one in between (not the network, not even the app's servers) can read it.
What E2EE does and doesn't hide
| Hidden | Often still visible (metadata) |
|---|---|
| Message content | Who you talked to |
| Attachments | When and how often |
| Calls (in good apps) | Sometimes your IP/number |
Metadata matters. "We can't read it" isn't the same as "we know nothing." The pattern of who talks to whom can reveal a great deal even without content.
The apps, roughly
| App | Note |
|---|---|
| Signal | Gold standard — E2EE default, minimal metadata, open-source |
| E2EE content, but lots of metadata to its parent company | |
| iMessage | E2EE between Apple users (green bubbles aren't) |
| Telegram "regular" chats | Not E2EE by default — a common myth |
Built on asymmetric crypto and key exchange, the same machinery as The TLS Handshake.
Related: Symmetric vs Asymmetric Encryption · Threat Modeling for Individuals · Your Digital Footprint