Here's a brief breakdown of the most widely used interfaces for computing devices.
Back in the olden days, parallel ports were used which could reach a bit rate of up to 2 MB per second. These were commonly used with PCs to attach printers.
SCSI interfaces (Small Computer System Interfaces) are used to attach peripherals to computers, and can transfer data at 80 MBs per second. More than one device can be attached via a single SCSI port.
ATA or (IDE - Integrated Drive Electronics) connects hard disk drives and CD-ROM drives and can transfer up to 100 MBs per second.
Serial Attached SCSI (SAS) supports data transfer at 3 GBs per second. Note that serial connections transfer data in a single stream in contrast to parallel interfaces.
Serial ATA (SATA) runs at 150 MBs per second.