What does swap memory refer to in the context of system memory?

Swap memory refers to a portion of the disk space that is utilized when the physical RAM (Random Access Memory) is fully utilized. It acts as an overflow space, allowing the operating system to move inactive pages from RAM to disk storage, thereby freeing up physical memory for active processes. This capability is crucial for maintaining system performance during times when the demand for memory exceeds the available RAM, enabling continued operation without immediate need for additional physical memory.

Using swap memory can help prevent system crashes and maintain functionality by providing a temporary storage area for data that is not currently in active use. It is particularly important in systems with limited physical memory, as it allows more applications to run simultaneously, albeit at potentially reduced speeds due to the slower access time of disk memory compared to physical RAM. Thus, this explanation underlines why the correct answer identifies swap memory as the data stored when physical memory is full.