During Google I/O 2014's keynote, Android Wear was officially announced. Android Wear extends the Android platform to wearables.
To use an Android Wear smart watch, it must be paired to a phone or tablet running Android 4.3 and up and has Bluetooth. The Android Wear app must be installed and used to pair the handheld device to an Android wear device (or an Android Wear emulator).
There were three smartwatches announced: the LG G Watch and Samsung Gear Live, which are already available for purchase and the upcoming Moto 360, which will be released in the coming weeks. Both the LG and Samsung watches have square faces while the Moto 360 has a round design.
Android Wear shows your Google Now cards and notifications from the apps installed in your handheld device. There are also apps that has integration to or run directly on the wearable. You can also use the Ok Google voice command to search, reply via voice, or do actions on the wearables (like Take a Note, Send a text, Navigate, and many more. It can also count your number of steps and get your heart rate (the Gear Live has this sensor while the G Watch does not).