Instead of calling CrazyFlie (as it's known) a tiny quadcopter, it might be more accurate to just describe it as a PCB that happens to also be able to launch itself into the air. Measuring a scant 10 centimeters per side, CrazyFlie uses its PCB as a primary structural component, which helps keep the size and weight to a minimum... In total, we're talking about only 20 grams.
Despite its tinyness, the quadcopter includes a charging port, radio, 3-axis accelerometer, two gyroscopes, and a lightweight 110 mAh LiPO battery that gives it about four and a half minutes of flying time: