SATA stands for Serial Advanced Technology Attachment, which is a type of computer hard drive that is the new standard as of 2009, replacing older IDE hard drives.
SATA hard drives connect to computer motherboards with a special SATA cable which is different from the ribbon-like cables used for IDE hard drives.
SATA hard drives require a special power plug which is smaller than the standard 4 pin power plugs used for IDE hard drives, case fans, and DVD drives.
SATA hard drives have the advantage of being slightly faster overall than their IDE counterparts, and also clutter the case less since the cords are much smaller.
SATA hard drives do not cost significantly more than older IDE drives for the same amount of storage, and may be cheaper in some instances.
Since 2004, SATA technology has moved to the external hard drive market with "eSATA" hard drives, which can connect to computers through a special eSATA port and achieve transfer speeds faster than firewire or USB 2.0.