Humans have been creating tools, gadgets, and other _______ for many thousands of years, ever since the _______ of fire-staring tools roughly 400,000 years ago. Like fire, the best inventions are _______ to our most important problems; they offer huge _______ and make life easier and happier. In addition, inventions such as the automobile developed into massive _______ that employ millions of workers. These companies spend billions on _______ to develop new gadgets, vehicles, medicines, and more recently, _______ plants and animals. Because the _______ and hardworking people who make these discoveries are so important to us, inventors can ask governments to grant them a _______. This document describes an invention and gives its inventor the exclusive right to sell it.