SCSI – Small Computer Systems Interface pronounced as ‘Scuzzee.’ It is an interconnect standard for PCs and servers linking to peripheral devices, such as disk drives and SSDs, and covers physical connections and data transfer. It was originally a parallel interface but later moved to a serial one. Serial-Attached SCSI (SAS) is a physical version of this and iSCSI is another version. See Wikipedia for a detailed look at SCSI.