Imagine having a 10-gigabyte hard drive in your cellphone or a terabyte of space on your laptop. Perpendicular recording, a new way of writing data to
a hard disk, creates the possibility for these kinds of capacities, just as we're approaching the physical limits of traditional recording methods.
Hard drives store information by changing the polarization of microscopic magnetic bits aligned end-to-end on a surface called a platter. But you can pack in only so many bits before they interfere with one another, randomly switching orientation and turning your data into noise.