A VPN is one of those tools that sounds more technical than it is. Strip away the advertising and the answer is simple: it is software that creates an encrypted connection between your device and a server somewhere else, then sends your internet traffic through that server instead of straight out of your home broadband. Everything else — the privacy talk, the streaming claims, the speed warnings — grows out of that one idea.

Most of what you read about VPNs is written by people selling VPNs. So here is a plain account of what one does, what it doesn't, and when it is genuinely worth the bother.

What a VPN actually does

Without a VPN, your device connects to websites fairly directly. Your broadband provider can see which sites and services you connect to, even if the contents of those pages are encrypted. The website, meanwhile, sees your IP address — the one your provider gave you, tied to your rough location.

A VPN changes both ends of that:

• Your traffic is encrypted between your device and the VPN server, so your provider sees a stream of data going to one address rather than a list of destinations.
• Websites you visit see the VPN server's address instead of yours, which usually means they think you are in a different city or country.

The effect is a swap of who can see what. Your provider loses sight of your browsing. The VPN company gains it. If that company keeps logs, you have simply changed who holds the record.

What a VPN doesn't do

This is where the marketing gets loose.

• It doesn't make you anonymous. If you log into an account, that account knows it is you. Your device and browser details still form a recognisable pattern.
• It doesn't stop most tracking. Cookies, pixels and login sessions follow you around the web whether you are on a VPN or not.
• It isn't antivirus. It won't spot a phishing email, a fake download or a dodgy app.
• It doesn't hide you from your employer. Monitoring software on a work laptop runs on the device, inside the tunnel.
• It can slow you down. Traffic takes a detour and encryption costs a little processing. On a good connection you may not notice; on a weak one you will.

Your broadband provider and your browsing

UK providers hold records of traffic passing through their networks and are required to retain certain kinds of data. That is the honest reason many people buy a VPN: to stop their provider building a picture of which sites they visit.

Whether that matters is a personal judgement. A VPN does not hide the fact that you are online, or how much data you use. It hides destinations.

Streaming, iPlayer and geo-blocking

Adverts like to suggest a VPN will open up every streaming library on earth. In practice it is a lottery. Streaming services actively detect and block addresses belonging to VPN providers, and the ones that work today often stop working next month.

It is also worth reading the terms you agreed to. Using a VPN to appear in another country usually breaches a streaming service's rules, and BBC iPlayer is intended for UK viewers with a TV licence. If a service blocks you, it is doing what it said it would do. Rules change, so check current terms rather than a forum post from three years ago.

The claim that a VPN gets you cheaper flights or hotel rooms is mostly outdated. Prices tend to follow your account, billing address and device, not the country your connection appears to come from.

Public Wi-Fi: less scary than it sounds

You have probably read that using café or hotel Wi-Fi without a VPN is reckless. That advice dates from an era when most websites sent data in the clear. Today nearly everything important — banking, email, shopping — uses HTTPS, which encrypts traffic between you and the site regardless of the network you are on.

The real risks on public Wi-Fi are fake hotspots set up to look like the venue's network, and networks that ask you to install something before connecting. A VPN adds a useful layer if you are on untrusted networks often, but it is not the difference between safe and unsafe.

When a VPN is genuinely worth it

1. You handle sensitive material and don't trust the local network. Hotel, airport and conference Wi-Fi all qualify.
2. You object to your provider logging your destinations and are willing to pay a company with a clear, published policy.
3. You travel and want a consistent connection that behaves the same in every country, including for services you already pay for at home.
4. You need to reach your own devices remotely — a home router running WireGuard, for example, so you can get at files or a home server from elsewhere. That is a different job from a commercial VPN, and often a better one.
5. Your employer requires it to reach company systems. That corporate VPN puts your laptop inside the company network.

If none of those apply, you probably don't need one, and that is a perfectly good answer. If your reasons touch on legal, employment or financial matters — a dispute, a workplace policy, a contract — take proper advice rather than relying on a general guide.

A practical way to start

1. Pick your reason first. A VPN for streaming is not the same as a VPN for work or privacy, and the best choice differs.
2. Read the privacy policy before the price. If it is vague about what gets logged, move on. Free services have to cover their costs somehow, so treat generous free tiers with suspicion.
3. Check the basics: apps for your devices, a kill switch that cuts the connection if the tunnel drops, and support for WireGuard or OpenVPN.
4. Test it properly. Note your IP address before and after, run a speed test, and try the sites and apps you actually use. Use split tunnelling if you only want certain apps routed.
5. Keep it updated, and switch it off when you don't need it. Leaving a VPN running permanently adds a point of failure and a monthly bill for a problem you may not have.

Treat a VPN like a lock on a door: useful, specific, and no substitute for knowing who you are letting in.

Photo: rawpixel / Pixabay