I used to treat every coffee shop network as a trap. If I needed to check email on public Wi-Fi, I assumed someone was reading over my shoulder digitally, and I either avoided it completely or rushed through it with a VPN switched on. That fear was not entirely wrong, but it was out of date. The internet changed under it, and my habits needed to catch up.
The risk in plain words is not that public Wi-Fi is magic. It is that a network you do not control can be observed, manipulated, or faked. Someone on the same network, or running a fake hotspot with a familiar name, could try to see unprotected traffic or steer you to a fake page. The question is how much of your traffic is actually exposed in that way today, and what a VPN really changes.
The risk in plain words
Years ago, much web traffic was unencrypted, which meant that someone on the same network could read a surprising amount of it. That is no longer the normal case for major sites. Most reputable websites now use HTTPS, which encrypts the connection between your browser and the site. That encryption does not hide which site you visited from the network operator, but it does make the contents of the pages and the details you enter much harder for a bystander to read.
That change does not make public Wi-Fi harmless. A fake hotspot can still try to trick you, an old or badly configured site may not use encryption properly, and other services on your device may behave differently. There are also risks that have nothing to do with encryption, such as someone looking at your screen, or a device that automatically connects to a network name it has seen before. Public Wi-Fi is lower risk than it once was, not no risk.
How it actually works
A VPN creates an encrypted tunnel from your device to the VPN provider, and then your traffic goes out to the internet from there. On a public network, that tunnel hides the contents and destinations of your traffic from the local network operator and from other people on that network. In that narrow sense, it does help, especially if you are worried about the network itself.
What a VPN does not do is just as important. It does not make a bad site safe, it does not stop phishing, and it does not make you anonymous. The VPN provider can see your traffic in the same way the network operator could have, so you are shifting trust from one party to another, not removing trust entirely. A free VPN that is vague about how it makes money deserves skepticism, because running that service costs money, and your attention or data may be the product.
What to actually do about it
First, keep your device and browser updated, and look for HTTPS on sites where you sign in or enter sensitive information. If a browser warns you about a certificate or a connection, do not click through the warning on public Wi-Fi to get to an important account. That warning is doing exactly the job it is meant to do.
Second, be careful about which network you join. Ask staff for the correct network name if you are unsure, and turn off automatic connection to open networks where you can. Avoid doing banking or other sensitive work on a network you do not trust if you can wait, not because every public network is hostile, but because waiting costs little and removes a whole set of questions.
Third, use a VPN when it fits a real need, and choose one deliberately. A reputable, paid VPN from a provider with a clear privacy policy makes sense if you regularly work on public networks, if you need to protect traffic from a local network operator, or if your work requires it. Turn it on before you connect to sensitive services, and do not assume it replaces strong passwords, two-factor authentication, or careful checking of links.
Finally, keep the honest both-sides view in mind. HTTPS changed the math a lot, so public Wi-Fi is not the free-for-all it once was. A VPN can add a useful layer, but it is a layer, not a cloak. I still use public Wi-Fi when I need to, I still use a VPN in situations where I do not trust the network, and I do not let either choice replace the basics that protect me everywhere.