Free Wi-Fi is awesome, no doubts here. But public networks hide numerous hazards, including even the risk of losing all the funds in your bank account.
The only foolproof way to protect yourself from data theft is to use mobile traffic to make online purchases or Internet banking. A few paid megabytes are a reasonable price for your account safety.
By turning off Wi-Fi, you resolve three issues at once: rapid discharge of your battery, automatic connection to a fraudulent network, and annoying ad emails. For additional protection against the latter, add an extension called DoNotTrackMe to your browser — it won’t let the device track your movements.
VPN, or Virtual Private Network, allows you to stay anonymous while online: websites you enter will see the virtual network IP, not yours.
Such networks, though, are mostly paid, and they slow down your connection. However, the price is usually not that high, and most VPN providers still have free services too.
Most devices will automatically remember and connect to the hotspot they used at least once before. Frauds could create their own access point with the same name and thus get access to your profile data or even, with certain artifice, to your finances.