Hard Disk Drives (HDD) are perhaps the unsung heroes of today's information technology. The rise and growth of the Internet search engines, social media, and cloud computing have been enabled, in part, by the inexpensive and massive storage capabilities that HDD technology provides. Less than 60 years after its invention by IBM in San Jose in 1956, the hard disk drive has seen an unrelentless, Moore's Law-like growth in storage density, as well as a concomitant decrease in price and form

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... The first HDD ever commercialized, IBM's RAMAC, had a mere 5 megabytes of storage, cost over a million dollar in today's currency, and weighted over a ton. Today's largest capacity disk drives hold 4 terabytes of data in a small 3.5 inch form factor and at a price similar to that of small household appliances such as a coffee maker, a hair dryer, or a toaster. Unlike other components of modern computers, the disk drive has moving parts, with a read/write head flying over a rotating disk. The thickness of the air gap between the flying head and the disk is now of the order of a nanometer or so, for velocities greater than 10 m/s, thus making the headdisk interface (HDI) one of the most advanced tribological systems available to the consumer in today's marketplace. As a result, great advances have been made over the last few decades in the field of nanotribology (the tribology of nanoscale systems)