Patents are highly educational and informative documents about interesting inventions.  A patent document tells you about the invention (usually including several drawings), who invented it, when it was invented, and why it is useful or better than other inventions already out there.  A patent grants exclusive rights to its inventor or applicant for a limited amount of time (normally a maximum of 20 years from the filing date).  In order for an invention to be granted the protection of a patent, the invention must be "novel," meaning it must be useful, non-obvious, and not already known.

Want to see what a patent document looks like?  Check out the Wright Brothers' "flying machine" patent (back from 1903), George Lucas' Star Wars Imperial fighter patent (a "design patent"), or a Disney theme park amusement ride patent (a "utility patent").