In drilling operations, an active pit is a reservoir or container used to hold drilling fluids or mud, which is a mixture of liquids and solids that are used to lubricate the drill bit, cool the drill string, carry rock cuttings to the surface, and maintain pressure in the wellbore. The active pit is where the drilling mud is actively circulating through, and it plays a crucial role in drilling operations by helping to control pressure and temperature in the wellbore and prevent hazards such as blowouts. The size and capacity of the active pit may vary depending on the type and depth of the well being drilled.