A mainframe computer is a robust computer designed for handling large amounts of data. Large amounts of memory, numerous concurrent computers, and high data input/output capacities are all features of mainframes. For high volume data analysis, database administration, resource monitoring, and transaction handling, large businesses and groups use mainframes. After supercomputers, mainframe computers are regarded as the second-most potent type of computer.

A mainframe computer's architecture places a strong emphasis on dependability and availability. Scalable mainframes are necessary so that businesses can expand their capability as required. Additionally, they are built with multiple components to prevent any malfunction from impairing the mainframe's functionality.

Most mainframes can go years without a reset thanks to the ability of administrators to hot-swap components into and out of a mainframe without shutting it off. A single computer can operate hundreds of virtual workstations thanks to support for sophisticated virtualization. All of this aids a mainframe in handling high-volume, mission-critical duties; banks, for instance, use mainframes to process thousands of operations per second throughout the day.

Mainframes employ specialist technology not found in laptop computers for home use. They make use of specifically created computers with many cores that can operate simultaneously in tandem with up to 32 processors. Additionally, they run specific mainframe operating systems like IBM's z/OS or Linux for mainframes.