Magnetic disks are storage devices that use magnetic material to record and retrieve data. They consist of a flat, circular platter coated with a magnetic substance, allowing information to be stored in the form of tiny magnetic fields. Common examples of magnetic disks include hard disk drives (HDDs) and floppy disks. Data is accessed by a read/write head that moves over the spinning disk surface. When the disk spins, the head detects the magnetic fields to read data or alters them to write new information. Magnetic disks are widely used in computers and other electronic devices for data storage due to their reliability and capacity.