How Does a VPN Work? A Plain-Language Guide
Open a banking app at a coffee shop and your phone sends dozens of small packets of data across the café’s Wi-Fi before you even see your balance. Anyone else on that network can, in theory, watch those packets go by. A VPN exists to make that watching pointless — but the “how” behind that sentence usually gets skipped in favor of vague marketing language. Here’s what’s actually happening on the wire.
What happens when you send data, with and without a VPN
Every request your device makes — loading a page, syncing an app, sending a message — gets broken into packets and routed through your local network, then your internet service provider (ISP), then across the internet to its destination. Without a VPN, your ISP can see which sites and services you’re talking to, and anyone sharing an unsecured Wi-Fi network can potentially intercept those packets in transit. Over 95% of web pages are now served over HTTPS, so the content of most traffic is already encrypted — but metadata (which domains you’re contacting, when, how often) usually isn’t.
A VPN adds a second layer: it wraps your traffic in its own encryption and routes it through a VPN server first, so your ISP and anyone on the local network see only an encrypted stream to that one server — not the sites behind it.
The handshake: how the tunnel actually gets built
Before any of your data moves, the app and the VPN server perform a handshake — a short exchange where both sides prove who they are and agree on a temporary set of encryption keys for that session:
- Your device contacts the VPN server and the two sides authenticate each other, so a stranger can’t impersonate the server.
- They negotiate session keys using public-key cryptography, without ever sending the actual keys in plain text across the network.
- The tunnel opens. From this point, every packet leaving your device is encrypted before it touches the local Wi-Fi or your ISP’s network.
This handshake typically takes a fraction of a second on modern protocols, which is part of why connecting doesn’t feel like a slow, separate step anymore.
What actually gets encrypted, and which protocols do it
Not all VPN protocols encrypt the same way. The two RunVPN uses under the hood — AmneziaWG and VLESS-Reality (XTLS-Vision, on the Xray engine) — are both built for a fast, stable connection with strong encryption, but they take different approaches to shaping the traffic pattern so it isn’t easily fingerprinted, which keeps the connection stable on restrictive networks.
| Protocol | Cipher | Design goal |
|---|---|---|
| AmneziaWG | ChaCha20-Poly1305 | Speed + obfuscated packet pattern |
| VLESS-Reality (XTLS-Vision) | TLS 1.3-based | Blends in as ordinary HTTPS traffic |
| Plain IKEv2/IPSec (reference) | AES-256 | Enterprise-standard, slightly heavier handshake |
Key takeaway: encryption strength across modern protocols is roughly equivalent — WireGuard-based designs use ChaCha20-Poly1305 rather than AES, and both are considered cryptographically strong. The real differences are speed, how the connection behaves on unstable networks, and how resistant the traffic pattern is to fingerprinting.
That last point matters more than most people realize. Traffic-analysis techniques have gotten sharper — some 2026 detection systems can fingerprint an unobfuscated WireGuard-style handshake in around 100 packets by analyzing timing and packet-size patterns alone, without reading any content. That’s why RunVPN pairs its protocols with connection-quality tuning designed to keep the session smooth and hard to distinguish from ordinary traffic — for a stable, private connection, not to target any specific network.
Where this actually matters day to day
- Public Wi-Fi. One widely cited industry study found that 43% of people who’ve used unsecured Wi-Fi networks have had their data compromised at some point. A VPN tunnel means the network operator — or anyone else on it — sees encrypted traffic, not your activity.
- Your ISP’s visibility. Even on your home connection, an ISP can normally see every domain you contact. A VPN narrows that visibility down to a single encrypted connection to the VPN server.
- Shared and unmanaged networks. Hotels, airports, and coworking spaces are exactly the environments where traffic interception is easiest — and where a tunnel matters most.
Worth remembering: a VPN protects the path your data travels, not the destination. If you log into a site, that site still knows it’s you — a VPN doesn’t erase your account activity, it protects your traffic from everyone in between you and that site.
Connecting with RunVPN: what happens behind the scenes
RunVPN is deliberately simple on the surface because the protocol work happens automatically:
- Download the app and sign in — with Google, email, or Telegram.
- The app fetches your configuration automatically from RunVPN’s server. There’s no manual setup, no config file to import, no code to scan.
- Tap connect. The handshake described above happens in the background, and your traffic starts flowing through the encrypted tunnel.
RunVPN runs a no-logs policy and supports up to 5 devices per account. Android is available today; iOS and desktop are coming soon.
FAQ
Does a VPN slow down my connection? Some overhead is unavoidable, since your data now takes an extra hop through a VPN server and gets encrypted and decrypted along the way. Modern protocols like the ones RunVPN uses are built specifically to minimize that cost, so the difference is usually small on a stable connection.
Can my ISP still see that I’m using a VPN? An ISP can typically see that you’re connected to a VPN server — there’s an encrypted connection to a known IP — but not which sites or services you’re using through it.
Does a VPN make me anonymous? No single tool makes anyone fully anonymous. A VPN encrypts your traffic and hides it from your local network and ISP, which is a meaningful, specific privacy improvement — but it’s not the same as anonymity across the entire internet.
Why does RunVPN use two different protocols? AmneziaWG and VLESS-Reality both prioritize speed and a stable, private connection, but they behave differently under different network conditions — having both under the hood means the app can pick whichever keeps your connection fastest and most reliable.
Ready to see it for yourself? Get RunVPN and read more about how VLESS-Reality and AmneziaWG work, or check out our no-logs approach.