Stardust was a space mission to collect material from the coma (tail) of a comet, specifically, the comet Wild 2. The probe was launched in 1999, flew by the comet 5535 Annefrank in 2002 and Wild 2 in 2004, collecting sample dust from the latter, then flew by Earth in 2006, ejecting a return capsule with the dust samples, also including interplanetary medium samples. These were recovered and have been under study.
After separation from the return capsule, the probe still orbited the Sun, with fuel, and a mission extension sent it to observe the comet Tempel 1 in 2011. After this flyby, the last of the fuel was deliberately burned and the transmitter was turned off, ending the mission.
Note that stardust is also a term for (some) presolar grains.