Mainframes first appeared in the early 1940s. The most popular vendors included IBM, Hitachi and Amdahl. Some recently considered mainframes as an obsolete technology with no real remaining use. Yet today, as in every decade since its inception, mainframe computers and the mainframe style of computing dominate the landscape of large-scale business computing. Mainframe computers now play a central role in the daily operations of many of the world’s largest Fortune 1000 companies. Though other forms of computing are used extensively in various business capacities, the mainframe occupies a coveted place in today’s e-business environment. In banking, finance, health care, insurance, public utilities, government, and a host of other public and private enterprises, the mainframe computer continues to form the foundation of modern business. The main difference between mainframes and supercomputers is their typical application domain – mainframes excel in reliable volume computing in domains requiring integer operations (e.g, financial, indexing, comparisons, etc). Supercomputers are design to excel in their ability to perform floating point operations – addition, subtraction, and multiplication with enough digits of precision to model continuous phenomena such as weather. Despite the continual change in IT, mainframe computers considered by many to be the most stable, secure, and compatible of all computing platforms. The latest models can handle the most advanced and demanding customer workloads, yet continue to run applications that were written in earlier decades. For those who think there is no use for the ‘big iron’ now, they would really be surprised. The truth is that we are all mainframe users in one way or another.