This first comprehensive history of software patenting explores how patent law made software development the powerful industry that it is today. Historian Gerardo Con Díaz shows how patent law has transformed the ways computing firms make, own, and profit from software. He demonstrates that securing patent protection for computer programs was a central concern among computer developers for more than half a century and traces how patents and copyrights became inseparable from software development in the Internet age. Software patents, he argues, facilitated the emergence of software as a product and a technology, enabled firms to challenge each other’s place in the computing industry, and expanded the range of creations for which U.S. intellectual property law provides protection. Powerful market forces, aggressive litigation strategies, and new cultures of computing usage and development transformed software into one of the most controversial technologies ever to encounter the American patent system.