HDDs are used either as the primary or secondary storage device in a computer. They are commonly found in the drive bay and are connected to the motherboard via an Advanced Technology Attachment (ATA), Serial ATA, parallel ATA or Small Computer System Interface (SCSI) cable, among other formats.

The main difference between a solid state drive (SSD) and a hard disk drive (HDD) is how data is stored and accessed. HDDs use mechanical spinning disks and a moving read/write head to access data, while SSDs use memory chips.