It is difficult to imagine a toy more ubiquitous than simple bubbles. The invention of soap--as we know it--dates back at least 400 years, and bubbles likely appeared soon afterwards. Fascinating to both children and adults, bubbles actually demonstrate real scientific principles and have been used in planning certain kinds of engineering designs. Bubbles as toys are available in simple forms like party favors, and in complex multi-bubble machines, safe and clean bubble guns, and countless other creations. The cleanest plaything around, bubbles are here to stay!