SAS offers optional compatibility with Serial ATA (SATA), versions 2 and later.

[5] The T10 technical committee of the International Committee for Information Technology Standards (INCITS) develops and maintains the SAS protocol; the SCSI Trade Association (SCSITA) promotes the technology.

In Fibre Channel, the port identifier is a WWPN and the device name is a WWNN.

People sometimes refer to a SCSI port identifier as the SAS address of a device, out of confusion.

[12] The Serial Attached SCSI standard defines several layers (in order from highest to lowest): application, transport, port, link, PHY and physical.

At the physical layer, the SAS standard defines connectors and voltage levels.

The physical characteristics of the SAS wiring and signaling are compatible with and have loosely tracked that of SATA up to the 6 Gbit/s rate, although SAS defines more rigorous physical signaling specifications as well as a wider allowable differential voltage swing intended to allow longer cabling.

[14] SAS-4 is slated to introduce 22.5 Gbit/s signaling with a more efficient 128b/150b encoding scheme to realize a usable data rate of 2,400 MB/s while retaining compatibility with 6 and 12 Gbit/s.

For example, an expander may include a Serial SCSI Protocol target port for access to a peripheral device.

SAS 1 defined two types of expander; however, the SAS-2.0 standard has dropped the distinction between the two, as it created unnecessary topological limitations with no realized benefit: Direct routing allows a device to identify devices directly connected to it.

Expanders assist in link-switching (as opposed to packet-switching) end-devices (initiators or targets).