What type of computer is primarily designed for supporting multiple users and running several programs at once?

Mainframes are powerful computers that are specifically designed to handle large-scale operations and support multiple users simultaneously. They can manage and execute several applications concurrently, making them ideal for environments such as large organizations, banks, and institutions where substantial data processing and transaction handling is required. Their architecture allows for high reliability, availability, and security, which are essential when many users depend on them for critical applications.

In contrast, supercomputers are optimized primarily for complex calculations and simulations rather than broad user access and multiprogramming. Minicomputers, while capable of supporting multiple users, typically handle less demanding tasks than mainframes and are not as powerful or robust. Workstations are high-performance computers designed for individual users running demanding applications, rather than supporting multiple users or processes concurrently. Hence, mainframes are uniquely suited for the requirements outlined in the question.