The first edition of this book was written by Jeffrey Schox for his course "Patent Law and Strategy for Innovators and Entrepreneurs" at Stanford University. After an introduction to intellectual property, it answers the questions: How does the patent system work? What is an invention? Is the invention patentable? When should the patent application be filed? Does the invention infringe any patents? and Who owns the patent application? This second edition has been updated to reflect any changes brought about by the recently passed America Invents Act ("AIA"), which will take effect March 2013 and transform the U.S. patent system from a "first-to-invent" system to a "first-inventor-to-file" system.