As controversial as it is revolutionary, Google Glass aims to change the way we see and use mobile computing.

Google Glass was announced at the Google I/O developer conference in the summer of 2012. The first wearable Android device wasn't available until some time later, but that's when we got our first look at what the "Explorers" would have in store for them.

At its essence, Glass is a spectacles-type device that has a small display that sits in front of and above your right eye, the equivalent of a 25-inch high-definition display from 8 feet. It's got a 5-megapixel camera beside it. And there's a bone-conducting speaker for providing audio. The second version of the Glass prototype comes with a mono earbud.

Glass is powered by Android but runs a simple, card-based user interface. Glass apps are referred to as Glassware. Data comes directly over Wifi, or via your a Bluetooth connection on your phone when you're out and about. You typically can get no more than a day's use before recharging.

Glass is about the journey. It's about figuring out what to do with this tiny screen and camera on your face. Thousands of Explorers wear Glass every day. More are coming.