DMA (Direct Memory Access) allows fast transfer of data between storage devices and memory without involving the CPU. It works by letting peripheral devices directly access and manage the memory buses. DMA was introduced on early PCs for floppy and hard disk I/O to improve transfer speeds. DMA controllers provide multiple independent channels and use signals like DREQ and DACK for handshaking during data transfers between devices and memory in continuous, cycle stealing, or interleaved modes. While fast, DMA requires additional hardware and data must be stored continuously in memory.