# File transfer glossary

Source: https://help.strongfolder.com/en/glossary/
Updated: 2026-11-05

> This glossary explains, in plain English, the technical terms you meet when sending files directly between devices — from peer-to-peer and WebRTC to STUN, TURN and NAT — and how each one shows up when you use StrongFolder.

Terms are listed A–Z. Each one links to the guide that explains it in context.

- **P2P** — Peer-to-peer: two devices exchange data directly instead of going through a central server that stores it. In StrongFolder the peers are the sender's and the recipient's browsers. See [P2P file transfer](/guides/p2p-file-transfer/).
- **WebRTC** — Web Real-Time Communication: a technology built into modern browsers for direct audio, video and data connections. StrongFolder sends files over WebRTC data channels.
- **Data channel** — The part of a WebRTC connection that carries arbitrary data — in StrongFolder, the pieces of your files.
- **Signaling** — The short exchange through a server that lets two browsers find each other and agree how to connect before a WebRTC connection opens. No file data passes through signaling.
- **ICE** — Interactive Connectivity Establishment: the procedure WebRTC uses to try possible network paths between two devices and pick one that works.
- **STUN** — Session Traversal Utilities for NAT: a server a browser asks 'what is my public address?', so it can be reached for a direct connection.
- **TURN** — Traversal Using Relays around NAT: a relay server used when a direct connection is impossible. It forwards the encrypted stream between the browsers; StrongFolder's relay does not store it.
- **NAT** — Network Address Translation: how home and office routers share one public IP address among many devices. NAT is the main reason direct connections sometimes need STUN or TURN.
- **DTLS** — Datagram Transport Layer Security: the encryption WebRTC applies to every data channel, so data is encrypted in transit.
- **End-to-end encryption** — Encryption where only the communicating ends can read the data. Cloud services that call themselves end-to-end encrypted still store your encrypted file; a P2P transfer does not store it at all.
- **File System Access API** — A browser feature that lets a web page write a whole folder tree to a place you choose. StrongFolder uses it to save received folders with their structure in Chrome, Edge and Opera on a computer.
- **Transfer link** — The address you send to the recipient. With StrongFolder it works while you are sharing; Stop Sharing or closing the tab ends it.
- **Upload speed** — How fast your connection sends data. In a direct transfer it is usually the limit: at 50 Mbit/s, 10 GB takes about 27 minutes.
- **ZIP** — An archive format that packs many files into one. Needed for email; unnecessary when you [send a folder as a folder](/guides/send-folder-without-zipping/).