Supercells are the least common type of thunderstorm, but they have a high propensity to produce severe weather, including damaging winds, very large hail, and sometimes weak to violent tornadoes.  What makes a supercell unique from all other thunderstorm types is that it contains a deep and persistent rotating updraft called a mesocyclone.  If the environment is favorable, supercell thunderstorms can last for several hours.

Sources: NOAA https://www.weather.gov/ama/supercell 

https://www.spc.noaa.gov/misc/AbtDerechos/supercells.htm