Software is the ubiquitous glue of the 21st century. Despite the well-documented difficulties of producing reliable large systems on time and within budget, the amount of software in all kinds of devices is increasing rapidly. For example, the amount of source code in a mobile handset is expected to increase to 10 million LOC by 2010. All kinds of new applications and infrastructures depend heavily on software, including social networking, Internet video, early-warning systems, medical information systems, and financial systems. These all have serious business implications. The computer industry changed dramatically and permanently when software took over in the 1980s. Software is profoundly changing the mobile phone industry with the rise of open operating systems such as Winmobile, Symbian, and Android. Such software growth affects healthcare, the automotive industry, and many others. The implications transcend engineering; they affect these industries' value chains and business models. One goal of this column is to build better quantitative insight into how software impacts various businesses. How the product uses the software and how the company built it are equally important.