Mars 3 was the first spacecraft to achieve a soft landing on Mars. The Soviet lander reached the Martian surface on December 2, 1971, after descending through the atmosphere using aerodynamic braking, parachutes, and retrorockets.
Its achievement came shortly after the Mars 2 lander crashed during its descent, making Mars 3 the first successful landing attempt. The spacecraft carried cameras, atmospheric instruments, soil-measuring equipment, and the small PrOP-M rover, which was designed to move on skis while tethered to the lander.
Mars 3 transmitted for only about 20 seconds after landing and sent back a partial image before contact was lost. A planet-wide dust storm was taking place at the time and may have contributed to the failure. This short transmission is why Mars 3 is remembered both as a historic success and a limited scientific mission.
A common mix-up is Mars 2: it was the first human-made object to reach the Martian surface, but it did so by crashing rather than landing softly.