The advances in magnetic recording which have enabled storage density to increase by more than 50, 000 times in 35 years are described. The fundamental principles of magnetic and magneto-optic recording are discussed. Current implementations of these technologies are presented, and future trends are projected. Storage densities of 1 Gbit/in2 are likely before the year 2000, and storage densities of 10 Gbit/in2 are expected in the first decade of the next century.