When you connect to a wireless network, your computer or mobile device sends and receives data the same way a radio does. Unless the data is encrypted by the network or sites you go to, anybody else with access to the network can “tune in” to view your search history, read your email messages, steal your credit-card info, and so on.
The video below shows how this attack is done and how the “Secure Wi-Fi” feature in Disconnect defends against attacks by upgrading popular sites and their widgets to HTTPS whenever possible so your data is encrypted.