A robot is a machine that is programmed to perform tasks automatically. The document discusses the building stage of creating a Lego Mindstorm NXT robot. Key components include the NXT brick which acts as the programmable computer brain, servos that provide movement, and various sensors that provide input. Students are divided into teams to begin constructing their first robot by applying what they learned about the basic building blocks and keeping the NXT brick accessible before moving to the programming stage.