Google Glass is a wearable computer with an optical head-mounted
display that is developed by Google with a mission of producing a mass-market
Google's program for developing a line of hands-free, head-mounted intelligent devices that can be worn by users as "wearable computing" eyewear was first released in 2013 (and costs approximately $1500).
Google Glasses look like a pair of normal eyeglasses, but the lens of the glasses has an interactive, smartphone-like display, with natural language voice command support as well as Bluetooth and Wi-Fi connectivity. Google Glass is powered by the Android mobile operating system and is expected to offer compatibility with both Android-powered mobile devices and Apple iOS-powered devices.
FYI: In aviation speak, a "glass" aircraft is one that has a digital cockpit, as opposed to a "steam gauge" or "rope start" cockpit with analog instrumentation. For example, "Since moving up to glass, I'd never want to fly an old steam gauge again."