Here's some various Lego NXT pieces and what they do. You'll hear these terms used a lot on this blog and a brief introduction to what they are seems in order.
NXT Intelligent Brick (Brick)
The Robot's "Brains"
This state-of-the-art programmable intelligent brick serves as the brain for the Lego robots. The brick features four input ports for taking in data and three output ports for distributing the data as commanded. You can transfer programs to the brick via USB cable or Bluetooth.
NXT Ultrasonic Sensor
The Robot's "Eyes"
The Ultrasonic Sensor helps the robot judge distances and "see" where objects are. The Ultrasonic Sensor is able to detect objects by emitting an ultrasonic pulse that bounces of an object and returns to the robot. The robot is then able to determine how far away that object is. The Lego NXT Ultrasonic Sensor has a range up to 250 cm (98 in).
NXT Light Sensor
The Lego NXT Light Sensor is sensitive and precise. It reads light intensity from the surrounding environment as well as the reflection from the infrared transmitter. The LED light source can be turned off for an accurate ambient light reading.
NXT Color Sensor
The Lego NXT Color Sensor is able to perform three unique functions. It acts as a color sensor, distinquishing among six colors; it works as a light sensor, detecting light intensities - both reflected light and ambient lightl and it works as a color lamp, emitting red, green, or blue light.
