A mortar and pestle are two tools used with each other to mill (grind) and mix substances.

The Mortar is bowl-shaped, and used to hold the substance to be ground.
 Mortars have smooth, rounded bottoms and wide mouths.
 The Pestle is a stick used for pounding and grinding.

Mortars and pestles are sometimes used in pharmacies to crush various ingredients to make drugs.
They can also be used in cooking to grind herbs.
A mortar and pestle are two tools used with each other to mill (grind) and mix substances.
The Mortar is bowl-shaped, and used to hold the substance to be ground.  Mortars have smooth, rounded bottoms and wide mouths.  The Pestle is a stick used for pounding and grinding. 
Mortars and pestles are sometimes used in pharmacies to crush various ingredients to make drugs. They can also be used in cooking to grind herbs.
Mortar and pestle