The Nexus One is a Smartphone from Google that uses the Android 2.1 mobile operating system. This is firmware version of the Android operating system adds a few aesthetic changes such as 'Live Wallpapers' which are animated in the background and react to different user inputs. The Nexus One has a 3.7 inch capacitive touch screen capable of handling multi-touch gestures. It has an illuminated trackball which can emit different colors of light based on the type of notification being received. A voice processor developed by Audience uses a second microphone (on the back) to reduce background noise during phone conversations. A 4-conductor TRRS style 3.5mm stereo headset jack is also provided, adding microphone function to the stereo earphones. The phone features a 5.0 megapixel auto-focus camera with LED flash and digital zoom, GPS receiver, Bluetooth 2.1 + EDR, and 802.11b/gWiFi capabilities. The Snapdragon processor allows for many advanced capabilities including 720p video Playback. There is built in hardware decoding for H.263, H.264 and MPEG-4 video, and is capable of playing MP3, AAC+, Ogg Vorbis, WAV, and MIDI audio. It has a micro USB port instead of the common mini-USB port and the micro SD card slot allows expansion up to 32 gigabytes of card storage.