A page table is a data structure used in computer operating systems to manage virtual memory. It maps virtual addresses to physical addresses, allowing the system to efficiently translate memory requests. Each process has its own page table, which helps the operating system keep track of which pages are in memory and which are stored on disk. When a program accesses memory, the page table is consulted to find the corresponding physical address. If the required page is not in memory, a page fault occurs, prompting the operating system to load the page from disk. This mechanism enables efficient memory management and multitasking in modern computers.