VPNs explained: what they do, and when they won't help

An honest guide from a site that tracks outages all day. Short version: a VPN is useful for privacy, but it can't fix a service that's down for everyone.

What is a VPN?

A VPN (virtual private network) is an app that sends your internet traffic through an encrypted “tunnel” to a server run by the VPN company. From there your traffic goes on to the websites you visit. The Wi‑Fi you're on and your broadband provider see only that you're connected to the VPN, not which sites you visit or what you send, and websites see the VPN server's address instead of yours.

How it works, simply

When you switch a VPN on, the app encrypts everything leaving your device before it goes out over your network. The VPN server decrypts it and passes it to the website, then encrypts the reply on its way back to you. Most sites already use HTTPS, which protects the content of your pages; a VPN adds a second layer that also hides which sites you're visiting from the local network and your provider.

The trade-off: you're trusting the VPN company with the information you're hiding from your provider. That's why its logging policy and independent audits matter so much (see below).

When a VPN helps

• Public Wi‑Fi. On café, hotel, airport and train Wi‑Fi, a VPN stops the network owner and other users from seeing which sites you visit.
• Privacy from your broadband or mobile provider. Without a VPN, your provider can see which websites you connect to. With one, it only sees that you're using a VPN.
• Sometimes, “down just for me” problems. Occasionally your provider has trouble reaching a particular site even though it's fine for everyone else. Because a VPN sends your traffic by a different route, it can sometimes get round this. If a site works on your phone's mobile data but not on your home broadband, this might be why.

When a VPN does NOT help

• If ChatGPT (or any service) is down for everyone, a VPN won't fix it. The problem is on the company's servers, and every route leads to the same broken service. Check the live status; if it says “Likely down”, the only fix is to wait.
• Usage limits and account problems. “You've reached your limit” messages are tied to your account, not your location.
• Getting round country restrictions on AI services. Using a VPN to use an AI service from a country where it isn't offered can break that service's terms and get your account suspended or closed. We don't recommend it.
• School or work network rules. Don't use a VPN to get round rules set by your school or employer, and never for anything illegal.
• Total anonymity. A VPN hides your address from websites, but if you sign in to an account, that site still knows who you are.

Also worth knowing: some AI services and websites show extra security checks to traffic from VPN servers, because many people share those addresses. If a site starts behaving oddly with a VPN on, switch it off for a moment to test.

How to choose a VPN

• A no-logs policy that has been independently checked. Anyone can say “no logs”. Look for audits by recognised firms, published or summarised on the provider's site.
• Speed and server locations. More nearby servers usually means better speed.
• Apps for all your devices, and how many devices one subscription covers.
• A kill switch, which blocks your traffic if the VPN drops, so nothing slips out unprotected.
• Price and a money-back guarantee, so you can try it properly. Be wary of “free” VPNs: running servers costs money, and some free services make it back from your data.

Our two top picks: NordVPN and ExpressVPN

If you've decided a VPN is right for you, these are the two we suggest. Both have had their no-logs claims checked by independent auditors, both include a kill switch, and both offer a 30-day money-back guarantee. Everything below can be checked on their own websites.

Facts checked on nordvpn.com and expressvpn.com on 18 October 2026. Prices and features change, so please check the details on their sites before you buy. “Top picks” is our opinion.