What Is a VPN?

When you connect to a VPN, your device establishes an encrypted connection — often called a "tunnel" — to a VPN server. All your internet traffic flows through this tunnel before reaching the open internet. This means your ISP can only see that you're connected to a VPN server, not which websites you visit or what data you send.

The VPN server acts as a middleman: websites see the server's IP address instead of yours. This is how a VPN masks your real location. Modern VPNs use robust encryption protocols like WireGuard, OpenVPN, and IKEv2 to ensure that even if someone intercepts your traffic, they cannot read it.

The entire process happens in milliseconds. When you tap "Connect" in a VPN app, the software initiates a cryptographic handshake with the server, negotiates encryption keys, and builds the tunnel — all before your first web request leaves your device.

A VPN protects you from several real threats. First, it reduces how much your Internet Service Provider (ISP) and other network observers can learn about your browsing, because your traffic is encrypted between your device and the VPN server.

Second, it helps on public Wi‑Fi networks, where attackers can attempt man‑in‑the‑middle attacks to steal passwords and financial information. A VPN encrypts data before it leaves your device, making intercepted traffic much harder to use.

Third, a VPN can help with travel continuity. When you connect to a VPN server in your home region, some services may treat your connection as coming from that region.

Finally, a VPN can be useful for comparison‑shopping because sites sometimes display different offers depending on location. Results vary, and a VPN is not a refund policy.

VPN protocols determine how your data is encrypted and transmitted. The most common protocols in 2026 are:

WireGuard — The newest and strong protocol. It uses state-of-the-art cryptography and has a lean codebase of roughly 4,000 lines, making it easier to reported for security flaws. Most top VPNs now use WireGuard as their default.

OpenVPN — The industry standard for over a decade. It's open-source, highly configurable, and runs on virtually every platform. Slightly slower than WireGuard but battle-tested with over 100,000 lines of reported code.

IKEv2/IPSec — Particularly good for mobile devices because it handles network switching (e.g., moving from Wi-Fi to cellular) seamlessly. Built into most operating systems.

Proprietary protocols — Some providers develop their own protocols. NordVPN's NordLynx is built on WireGuard, while ExpressVPN's Lightway is a custom protocol designed for speed and low battery impact.

It's important to understand the limits of a VPN. A VPN does not make you invisible online — it can improve privacy, but it’s not a silver bullet. If you log into an account (Google, banking, social apps), that service can still identify you. A VPN also won’t protect you from malware, phishing emails, or installing unsafe software.

A VPN usually does not make your internet faster. Because your traffic is encrypted and routed through an additional server, there can be some speed reduction. In some cases, performance can improve if your ISP is throttling certain traffic patterns, but that’s not intended.

Finally, a VPN does not replace good security hygiene. You still need strong, unique passwords, multi‑factor authentication, and up‑to‑date software.

When selecting a VPN, prioritize providers with a clear, published privacy policy and a credible approach to logging. If a provider publishes third‑party audits, read the reported scope and date.

Server coverage matters: more locations can mean more options and potentially better performance, but coverage alone doesn’t ensure better performance.

Speed depends on your distance to the server, protocol choice (WireGuard is often faster than OpenVPN), and network congestion. Treat any speed claims as approximate.

Jurisdiction can matter for privacy and legal process, but it’s not the only factor. What a company can log, and what it chooses to log, matters more than marketing.

Finally, consider device limits, platform support, and support quality. Our VPN reviews summarize publicly available information, but you should verify key details on the provider’s site before purchasing.

You do not need a lab to confirm the basics:

1. Note your public IP with the VPN off using our What Is My IP tool.
2. Connect the VPN, pick a nearby US city if you only want privacy (not a different country).
3. Reload the IP tool. The ISP name and city should match the VPN, not your home broadband.
4. Run a DNS leak check and a WebRTC leak check.
5. If either test still shows your home ISP, switch protocol (try WireGuard), turn on IPv6 leak protection if the app offers it, and retry.

If those checks fail, the VPN is not doing the job the marketing described. Use the refund window.

This guide is public-source research: how tunnels work, what US ISPs can see, and what a consumer app can and cannot hide. First-party tests appear on individual review pages when a dated How-we-tested note is published. Until then, treat provider speed or streaming claims as unverified marketing. Read how we rank for the difference.