Large computers are classified as

Computers are grouped by physical size and processing power into a scale that runs from the smallest, single-user machines up to the largest, most powerful systems. At the top of that scale sit large computers built to process enormous volumes of data and support hundreds or thousands of users and terminals at the same time, typically used by banks, large corporations, and government agencies for critical, high-volume processing. This category of large, high-capacity machine is what "large computers" in this classification refers to.

A desktop computer is a small, single-user machine designed for one person's personal or office use, sitting at the opposite end of the size scale from a large computer. Microcomputers is simply the broader technical term for the same category of small, single-user machines that includes desktops and laptops, so it also describes small rather than large systems. Minicomputers occupy a middle tier, more powerful than a microcomputer but still considerably smaller in scale and processing capacity than the large, enterprise-level machines described here, historically used by mid-sized organisations for departmental computing rather than for the largest workloads.

When ranking computer categories by size, keep the order in mind from smallest to largest: microcomputers (including desktops), minicomputers, and then the large, high-capacity machines used by major institutions.