Database server processes are called virtual processors because the way they function is similar to the way that a CPU functions in a computer. Just as a CPU runs multiple operating-system processes to service multiple users, a database server virtual processor runs multiple threads to service multiple SQL client applications.
A virtual processor is a process that the operating system schedules for processing.
Figure 15 illustrates the relationship of client applications to virtual processors. A small number of virtual processors serve a much larger number of client applications or queries.