This chapter discusses the surface of the rich and complex subject, and unfortunately must make generalizations which inevitably can be contradicted by specific instances. Courts and policy-makers have had difficulty comprehending the issues in the interoperability debate, not so much because the legal arguments are difficult—indeed, they are quite straightforward—but because of the complexity of the underlying facts: computer technology and the computer industry. From a state of relative anarchy in the 1950s, the industry fell under the domination of International Business Machines (IBM) during the 1960s and 1970s. In general, a computer system comprises two elements: the hardware and the software. The hardware—the physical computer equipment—consists of three basic elements: the central processing unit, memory, and the input/output system. IBM also leveraged the widespread acceptance of the System/360-370 architecture into control of the computer networking market. The electrical pulses from the input/output system are transmitted to the next hardware element, the central processing unit.