The mechanics
A VPN builds an encrypted tunnel between your device and a server run by the VPN company, and all your traffic goes through it. The network you are sitting on, whether a coffee shop, a hotel or your home internet provider, sees only that you are connected to a VPN. The sites you visit see the VPN server's address instead of yours. Everything your internet provider used to see, the VPN company can now see instead. You have not removed the need for trust, only moved it.
What encryption you already have
Most of the web is already encrypted. When the address bar shows a padlock, anyone watching the network can see which site you are visiting but not the pages, the passwords or the card numbers. A VPN's real additions are hiding the list of sites from the local network and your provider, and hiding your location from the sites.
What it does not do
- It does not stop tracking by cookies, by browser fingerprinting or by the accounts you are logged in to, which is how most tracking works.
- It does not hide you from any site you sign in to, because you have just told that site who you are.
- It does not block phishing, malware or a bad download, whatever the bundle of extras claims.
- It does not make illegal activity untraceable, since providers can be compelled to hand over whatever records they hold.
When it earns its fee
It is worth having on networks you do not control, when you would rather your internet provider not keep a record of the sites you visit, and when traveling in countries that block services you rely on. Reaching your home streaming library from abroad works intermittently and may breach the service's terms. A work VPN is a different animal. It connects you to your employer's network, and your employer can see what passes through it.
Choosing one
Pay for it. A reputable service costs from a few dollars to about ten dollars a month, and a free one has to make money from something, which is generally your browsing data. Look for a no-logs policy that has been verified by an independent audit, a kill switch that blocks traffic if the tunnel drops, and apps for every device you own.
Tip Be wary of review sites that rank VPNs, since many are owned by VPN companies or paid by commission. An audit report published by a named security firm tells you more than any top-ten list.
