It's not necessarily a good idea to walk into a coffee shop and use the free public Wi-Fi without protecting yourself first. For sure, it's easy and tempting, but it's risky.
Networks like those are relatively easy to snoop on, which means people nearby -- even in the same coffee shop as you -- can easily see what you're doing, leaving personal data such as credit card numbers and passwords vulnerable to theft.
There's an easy solution to protect yourself: Use a virtual private network (or VPN for short.) A VPN allows you to surf the network securely, as if you're connecting to the internet through a steel tunnel.
VPNs are widely used by corporations around the world who need to keep company data private, particularly if employees are out using these public Wi-Fi networks. You can protect yourself in the same way by using a VPN on your personal computer or phone.