How a VPN works (and why it matters)

Learn what your VPN is really doing so you can use it to the fullest.

Senior Reporter

Updated Thu, April 2, 2026 at 12:13 PM UTC

If you buy something through a link in this article, we may earn commission.

Cyber Security Analyst Ensuring Secure Virtual Network Access On Laptop (AndreyPopov via Getty Images)

Connecting to one of the best VPNs before you get online protects your anonymity, keeps your browsing activity hidden from your ISP and lets you explore the web from perspectives all over the world. Yet despite that multitude of benefits, it's strangely hard to find clear information on what your VPN actually does when you turn it on. That's a problem, since knowing how a VPN works isn't just trivia — it's key knowledge you can use to pick a VPN and get the most out of it.

In this story

You might already know that a VPN is a sort of digital mask that conceals your online fingerprints and makes you harder to identify. You may have heard that your VPN works by encrypting your connection so it's impenetrable to outsiders. That's a start, but like everything else on the internet, it's a bit more complicated.

This article is the definitive guide to how a VPN works and what you can do with one. I'll go into some technical details, but in a way that doesn't require a PhD to understand. By the end, you'll be equipped to cut through the hype and find a VPN you'll love to use.

What is a VPN?

VPN stands for "virtual private network," which makes more sense when you know how they were first used. Initially, a VPN was a way to access a closed network (such as the internal net at an office or school) from a remote location without leaving the gate open behind you. Remote workers still use them this way, but for this article, I'm talking about the commercial VPNs — like Proton VPN and ExpressVPN — that evolved from that original technology.

Instead of a closed network, a commercial VPN gives you secure access to the entire internet. Typically, it's sold on a subscription model and operated through an app called a VPN client, which works on computers, phones and other devices.

The client is the main thing you'll interact with, but it's just the tip of the iceberg. The bulk of a VPN's infrastructure is its network of servers in various countries. These servers mediate between your device, your ISP and the websites you visit, and provide the false IP addresses you can use to conceal your identity online.

What does a VPN do?

When you open your VPN app and connect to a server, the VPN becomes a stopover point for all data moving to and from your device. The client encrypts the signals at your device and sends it on to your ISP, along with just enough information for the ISP to forward it to a VPN server — like how a mail carrier can only see the address label on an envelope, not its contents.

Once your data hits the VPN server, it's decrypted and sent along to its destination. When the site you're viewing gets your request and sends it back to you, the response gets re-encrypted at the VPN server first before going back to you via your ISP. In the end, nobody except you and the VPN provider has enough information to connect you with your activities online.

What can you use a VPN for?

Getting on the internet is pretty convoluted as it is, and adding a VPN into the mix does make things slower (though not by much if you use a good service). But in exchange, you get reliable anonymity, which prevents ad services from building profiles on you and provides the kind of safety that's paramount for journalists and activists.

A VPN also gives you control over your virtual location. Changing locations doesn't just mean nobody can find the real you — it also means websites will show you content that's meant for people in other regions. If you're interested in a streaming show, a particular event or a special deal that's only available in a certain country, a VPN can get you there. It's also useful for getting around government blocks like the Great Firewall of China.

Getting technical: How a VPN really works

If you just came here to understand what everyone's talking about when they discuss VPNs, you can stop here. But if you're interested in peeking behind the curtain, I'll use these next sections to unpack VPNs from a technical perspective — starting from how the internet operates, then explaining what exactly I mean when I talk about an "encrypted tunnel."

How the internet works

To grossly oversimplify, the internet consists of millions of servers hosting websites, plus ISPs that create pathways between those servers and the computers and phones we use every day. Two core inventions make that possible: the Transmission Control Protocol (TCP) and Internet Protocol (IP).

Internet Protocol is the "IP" in "IP address." And it is an address: just like your mail goes to a combination of a number, street address, city and ZIP code that could only identify your house, each IP address is unique to a single online device like your phone or laptop. TCP is the mail truck in that metaphor, handling the actual transmission of signals between IP addresses.

When you type a URL into your web browser or click on a link, your computer asks your modem to contact your ISP. Your ISP gets the request and checks which IP address is connected to the URL you asked to see — information stored on a domain name server (DNS) usually controlled by the ISP itself. Once it knows where to go, the ISP contacts the server at the matching IP address and asks to see some of the content stored on it.

The server then finds the content you're looking for and sends it back through the entire process — first to your ISP, then to your modem and browser. Astoundingly, this all happens in a few seconds. ISPs these days are very good at finding the most efficient possible routes between users and websites.

Of course, this is all assuming you're not using a VPN. If you are, then two steps in the process become even more critical: your modem's first contact with your ISP and your ISP relaying information back to your browser.

How a VPN tunnel works

It's often said that a VPN creates an "encrypted tunnel" between your device and its server. The entrance to the "tunnel" is the VPN client. Before any data travels from your device to your modem, the client scrambles it with a cryptographic cipher, leaving only the information necessary to move the data along to its destination. This information is enough to get it to the VPN server, where the encryption is removed — thereby taking it out of the "tunnel."

How does your request find the VPN server without being traceable back to you? It uses a relay system. The internet relies on bouncing information between nodes, and even the simplest requests tend to go through several transfers. When your data travels in a VPN tunnel, each node only gets enough information to send it to the next node. No onlooker could ever see both its origin and destination.

It's the same in reverse. When your ISP gets the data you asked to see, it sends it to the VPN server, which it thinks made the initial request. After the VPN encrypts the data, it again uses your ISP to get back to you — but because of the encryption, your ISP doesn't know it's the same data.

How VPN encryption works

The most important technology underlying VPNs isn't the clients you use to operate them — it's the VPN protocols that handle encryption and communication behind the scenes. The whole dance of encryption, routing and decryption that we discussed in the last section is managed by protocols. A VPN protocol is a set of instructions that serves as a common language for VPN servers, letting them interact with ISPs and websites they've never seen before.

Among other things, the VPN protocol determines what sort of encryption your VPN will use. There are many different ways to encrypt and decrypt data, but a common approach is to combine two ciphers. Asymmetric encryption, which is more secure but slower, is used first to safely exchange decryption keys. After that, faster symmetric encryption can be used, since the layer of asymmetric encryption protects its one vulnerability — the use of the same key to encrypt and decrypt.

OpenVPN, WireGuard and IKEv2/IPSec are three of the most common protocols still in use. All three use either the "bank-grade" encryption AES-256 or an equivalent like ChaCha20.

Why you should care

Once you're armed with a technical knowledge of what VPNs do behind the scenes, you'll be able to evaluate providers for yourself instead of relying on the hype. For example, you now know that a VPN's primary job is to disconnect you from the names and locations of websites you visit; most of the websites themselves are encrypted already because of HTTPS.

You also know that there's nothing particularly special about military-grade/bank-grade encryption, since pretty much everyone is using AES-256. And you're aware that tunneling only encrypts information between your device and the VPN server — so if you post your real phone number on social media with your VPN turned on, expect to still get spammed.

About our ads