Software engineering is the profession that creates and maintains software applications by applying technologies and practices from computer science, project management, engineering, application domains, and other fields. Software is the set of instructions that enables computer hardware to perform useful work. In the last decades of the twentieth century, cost reductions in computer hardware led to software becoming a ubiquitous component of the devices used by industrialized societies. Software engineering, like traditional engineering disciplines, deals with issues of cost and reliability. Some software applications contain millions of lines of code that are expected to perform properly in the face of changing conditions. As of 2002, the U. S. Bureau of Labor Statistics counts 675,000 computer software engineers holding jobs in the U.S., and there are estimated to be about one-and-a-half million practitioners in the E.U., Asia, and elsewhere; these figures are about 60% of the number of practitioners engaged in traditional engineering. SE pioneers include Barry Boehm, Fred Brooks, C. A. R. Hoare, and David Parnas. There is extensive debate about what SE is, who qualifies as an SE, who sets the standards, etc.