You probably know what a VPN does – you may even subscribe to a VPN service – but if you’re wondering how they work, we have the answers you’re looking for.

How does a VPN change my location?

VPN stands for Virtual Private Network. The way it works is that you sign up for a VPN service and this dictates the choice of servers.

As there are different reasons to use a VPN, such as watching BBC iPlayer when abroad, you might choose a server in your own country or you might specifically want to use one in a different country to get around blocked content.

Whichever you choose, your internet connection in routed out through your ISP (internet service provider) and then via your chosen VPN server to the final destination, typically a website.

The website thinks that the original request comes from the VPN server and not your computer, so this is how it can appear that you’re located, say, in California or New York when you’re actually sitting in Manchester or London.

How does a VPN work?

How does a VPN keep my data private?

The connection between your computer and the VPN server is encrypted. That means that anyone attempting to look at the data being sent to and from your computer (even your ISP) will find that they can’t because none of it is sent as plain text.

Only your computer and the VPN server have the encryption and decryption keys. When the data arrives at the VPN server it is decrypted and sent on to the website or other server as appropriate.

The information can still be encrypted, however, but whether it is or not will depend on the site or service you’re using.

For example, if you’re using a website to buy a product or transfer money / pay a bill, then the connection should be encrypted using HTTPS. You should see this in the address bar of your web browser along with a padlock symbol.

Similarly, if you use Gmail and send an email to another Gmail user, the data is encrypted for its entire journey. When you use a VPN service as well the data is encrypted a second time, but only between your computer and the VPN server.

All of this happens transparently and automatically, so you wouldn’t even know it’s happening. However, the downside to a VPN is that the speed of the connection could be slower than when you connect to the internet normally.

Speed depends on many factors, but if you’re downloading videos using a VPN, it could take significantly longer than without one.

Does a VPN affect every app on my computer?

It depends. Usually it does because you’ll download some software from your VPN provider, sign in with your account details, pick a server and then turn on the VPN connection, as you can see in this screenshot from NordVPN, currently our recommendation for the best VPN:

How does a VPN work?

This affects every app which connects to the internet, including your web browsers, games and even Windows Update.

There are some VPN services that require no software at all. For example, Hidden24 works with each operating system's native VPN settings so you enter your account and server details and you can use it on Windows, Linux, iOS, MacOS and Android.

However, if you use a web browser with a built-in VPN (such as Opera) or you install a browser add-on in Chrome, Firefox or another one, then only data sent to and from that browser will be affected by the VPN. Any other app (including other web browsers) won’t use the VPN connection.

This approach has pros and cons. The advantage is that you can securely browse with a VPN, but not slow down the connection speed for other apps.

The disadvantage is that you might forget that other browsers won’t use the connection and won’t be afforded the same protection. Also, browser extensions are reported to be less safe. According to TheBestVPN, 70% of Chrome add-ons leak your DNS information. That means sites you visit can potentially be traced back to you, which isn’t ideal.

It’s worth noting that you’ll have to install the VPN software on every computer or device on which you want to be protected. The only workaround to avoid having to protect each device individually is to buy a router that supports VPN connections – you’d then enter your login details into the router’s interface which would then apply the encryption to every device that connects to the internet.

There are again pros and cons of this method. The VPN connection would be used permanently for every device, which may cause problems. For example, if you’re trying to stream video through a set-top box, the connection speed via the VPN may be too slow and be forever stopping to buffer.

The advantage is that your smart home devices (security cameras, smart speakers etc) also benefit from the VPN encryption, which should mitigate any security holes they may have. Typically there’s no other way to use a VPN with such devices.

Just remember that the VPN router method applies only when devices are connecting via the router. Phones and tablets must be connected via Wi-Fi: when they connect via 3G or 4G, the VPN connection won’t be used.

To see a list of the providers we recommend, check out our guide to the best VPN services.