Recording & retrieval via conductive coil called a head
May be single read/write head or separate ones
During read/write, head is stationary, platter rotates
Write
Current through coil produces magnetic field
Pulses sent to head
Magnetic pattern recorded on surface below
Read (traditional)
Magnetic field moving relative to coil produces current
Coil is the same for read and write
Read (contemporary)
Separate read head, close to write head
Partially shielded magneto resistive (MR) sensor
Electrical resistance depends on direction of magnetic field
High frequency operation
Higher storage density and speed