How does virtual memory allow programs to use more memory than the installed RAM?

Virtual memory allows programs to operate as if they have access to more memory than is physically installed as RAM by creating a system of large, addressable memory spaces.1

Rather than relying solely on physical memory, the operating system allocates a portion of the computer's hard disk to act as an extension of the system's main memory. The computer automatically manages this process by copying blocks of code and data between the hard disk and the RAM as they are required by the program. This technique remains efficient because of the principle of locality of reference, which ensures that the system only needs to move the specific data currently in use into the faster physical memory.21