A spade is a digging tool primarily used to 'cut' the soil. It can also be used to lift out the loosened soil, but that is a better job for a shovel.
Spades historically have been made with wood, wood with metal edges and also with full metal blades. Spades depicted on the Bayeux Tapestry are asymetrical with the handle running up one side of the tool. Later spades appear closed to modern spades.