Serial Advanced Technology Attachment (SATA) is a computer bus primarily designed for transfer of data between a computer and storage devices (like hard disk drives or optical drives).
The main benefits are thinner cables that let air cooling work more efficiently, faster transfers, ability to remove or add devices while operating (hot swapping), and more reliable operation with tighter data integrity checks than the older Parallel ATA interface.
It was designed as a successor to the legacy Advanced Technology Attachment standard (ATA), and is expected to eventually replace the older technology (retroactively renamed Parallel ATA or PATA). Serial ATA adapters and devices communicate over a high-speed serial cable.
The standard interface for SATA controllers is Advanced Host Controller Interface (AHCI), which allows advanced features of SATA such as hot plug and Native Command Queuing (NCQ). If AHCI is not enabled by the motherboard and chipset, SATA controllers typically operate in "IDE emulation" mode which does not allow features of devices to be accessed that are not supported by the ATA/IDE standard.
Windows device drivers that are labeled as SATA are usually running in IDE emulation mode unless they explicitly state that they are AHCI. Windows XP does not officially support AHCI although some proprietary device drivers may allow it. Windows Vista and the current versions of Mac OS X and Linux have native support for AHCI.
SATA offers performance as high as 3.0 Gbit/sec per device with the current specification. SATA uses only 4 signal lines, allowing for much more compact (and less expensive) cables compared with PATA. It also offers new features such as hot-swapping and native command queuing. There is a special connector (eSATA) specified for external devices, and an optionally implemented provision for clips on internal connectors. SATA drives may be plugged into Serial Attached SCSI (SAS) controllers and communicate on the same physical cable as native SAS disks. SAS disks, however, may not be plugged into a SATA controller. -- Source: Wikipedia.