When you access the data on your hard drive, the information comes via the IDE (Integrated Drive Electronics) controller on the drive's own circuit board - though in the first hard drives, you'd need a separate controller card in the PC and the drives themselves had less intelligence. The IDE controller can best be described as the brains of the drive. The drive is connected to the motherboard by the EIDE (Enhanced IDE) Sata port. These ports in turn are controlled by the controller chip on the motherboard.

Before the widespread adoption of Sata, the most common terms used to describe hard-drive interfaces were IDE and ATA - both of which mean the same thing. Because Western Digital coined the term 'IDE', other manufactures had to come up with an alternative, and so AT Attachment was born; the AT (Advanced Technology) part refers to the AT bus architecture in the IBM PC/AT.
In fact, there are seven versions of the ATA interface and all are backwards compatible, with the chief difference being the speed of the connection.