The Selectively Compliant Articulated Robot Arm (SCARA) is usually a 4-axis industrial robot. The kinematics is like a human arm, with the first joint been referred to as the shoulder and the second as the elbow. These two joints allow to move in the x- and y-axis. The third joint is a translation joint and moves along Z. The last joint is Theta and gives a rotation around the z-axis.
SCARA robots reportedly offer the best price/performance ratio as regarding speed. They are faster than cartesian robots (because they move less mass) and 6-axis robots (because they have fewer joints and because they are usually stiffer).
They are very common in pick-and-place, assembly, and packaging applications. The electronic printed circuit board industry, in particular, use large numbers of SCARAs for placing semiconductor ICss and other components on the circuit boards of computers and related equipment.
