Descriptor tables are crucial data structures in an operating system, particularly in x86 architecture, for managing and organizing the CPU's understanding of memory, tasks, and interrupts. There are three primary descriptor tables: the Global Descriptor Table (GDT), the Local Descriptor Table (LDT), and the Interrupt Descriptor Table (IDT). Additionally, the Task State Segment (TSS) is closely related to these tables, playing a critical role in task management.