Philips Hue is a controllable LED system that allows users to control the color and brightness of a Philips Hue LED bulb.  There are 4 parts to the system:

1. The LED bulb
2. The Bridge.  From the Hue how it works section "It's the 'bridge' between your bulbs and your smart phone app. And it can link up to 50 bulbs at a time.

   To connect your bridge, first power up and then plug into the back of your wireless router, using the network cables provided. The blue lights go on one by one. When all four lights stay on continuously, you're ready for action."

3. Mobile Device app (Apple and Android)

This system allows you to adjust the color of the Philips LED lamps, how bright they are, and if they are on or off. 

From the Apple Store:

"Create your personal wireless lighting environment with the Philips Hue connected bulbs and wireless bridge. And control it all with your iPhone or iPad from wherever you are. You can connect up to 50 Hue light bulbs to a single system, while using as much as 80% less energy than traditional bulbs.

Each Hue light bulb delivers 600 lumens and produces all shades of white, from warm to cold, and a wide variety of colour. Each bulb uses 80% less power than a traditional light bulb.

It's easy to extend your lighting system with additional single bulbs. All you need is the bridge that comes with the Starter Pack."