Mainframe computers were the first type of computers developed in the 1940s. They were extremely large with the ability to process and store massive amounts of data. Mainframes were used by banks, large corporations, and government agencies due to their high-level computing power, increased processing power, reliability, availability, scalability, and security. While expensive initially, mainframes were designed to last 5-10 years with low ongoing costs. Modern mainframes continue to offer significant advantages over cloud computing including high-end performance, security, reliability, and customization.