A Wi-Fi hotspot is a convenient tool for travelers who want to keep in touch with friends, family or the office while away from home. However, most users don't realize that Wi-Fi hotspots are vulnerable to hackers who set up what's known as "evil twin" networks, or phony Wi-Fi hotspots, to steal your personal information. Just as you wouldn't leave the front door to your home open to intruders, the Miami-Dade Consumer Services Department advises Wi-Fi users not to leave their computers, smartphones or any other Wi-Fi devices exposed to criminals.