Don't expect to see a flashing screen with a siren, or a Dennis Nedry type pop-up saying "Ah ah ah. You didn't say the magic word." Instead, the warning will appear when you head to Settings > Wi-Fi.
Under the Wi-Fi network's SSID, you will find the words Security Recommendation. Tap the 'i' button and you will be warned that the Wi-Fi network you are using is unsecured. The actual warning reads, "Open networks provide no security and expose all network traffic."
Many of us use unsecured Wi-Fi networks every day without giving it a second thought. For example, some large cable T.V. firms like Xfinity (Comcast) and Time Warner offer Wi-Fi Hotspots for their customers dotted throughout their coverage area. While the cable firms usually flash a reminder that their network is not secure, not all unsecured Wi-Fi networks do. And that is where Apple's new feature serves as a handy reminder to watch what you're saying.