Hackers can eavesdrop on your computer use, intercepting passwords and dropping ransomware onto your device if you use WiFi. A flaw called KRACK Attack was recently discovered by a Belgian security researcher. https://www.krackattacks.com It defeats the WPA2 encryption scheme of supposedly secure, password-protected WiFi access points (hotspots).
You should continue to use passwords for our WiFi connections but cannot assume you are safe until you apply updates to your devices.
UPDATE: For information on fixes that stop KRACK from letting hackers intercept what you send and receive over WiFi, see: KRACK Attack Threatens All Wi-Fi Networks: What to Do
To limit the potential damage caused by KRACK and future breaches, be sure that you have next-generation protection against viruses and ransomware, plus be sure that your computers are regularly backed up.
To protect your use of WiFi anywhere, you can subscribe to a Virtual Private Network (VPN) service. With VPN on your laptop or phone, everything you send or receive through a WiFi hotspot is encrypted a second time using your own private password. We recommend Private Internet Access as a good, subscription-based VPN. One subscription covers multiple devices.