The data displays shipment numbers for hard disk and solid state drives (HDDs and SSDs) worldwide from 2015 to 2021. Estimates suggest that shipments of HDDs will decline, falling to 395 million units shipped in 2017. SSD shipments are expected to increase to 190 million shipped units that same year. Hard disk drives are data storage devices used for storing and retrieving digital information. They are non-volatile memory, meaning that they retain data even when unpowered. The main competing technology for secondary storage is flash memory in the form of solid state drives.
