A trailing-arm suspension is an automobile suspension design in which one or more arms (or "links") are connected between (and perpendicular to) the axle and the chassis. Simple trailing-arm designs in live axle setups often use just two or three links and a Panhard rod to locate the wheel laterally.
A semi-trailing arm suspension is an independent rear suspension system for automobiles in which each wheel hub is located only by a large, roughly triangular arm that pivots at two points. Viewed from the top, the line formed by the two pivots is somewhere between parallel and perpendicular to the car's longitudinal axis; it is generally parallel to the ground.
Trailing-arm and multi-link suspension designs are much more commonly used for the rear wheels of a vehicle where they can allow for a flatter floor and more cargo room. Many small vehicles feature a MacPherson strut front suspension and trailing-arm rear axle.