Excavation is the act or process of digging, especially when something specific is being removed from the ground. Archaeologists use excavation to find artifacts and fossils.
There are many types of excavation, but they all involve digging holes in the earth. Mining for coal, gold, or diamonds all require excavation, and before buildings and houses can be built, there is often some excavation that's done before a foundation can be poured. The Latin source of excavation is excavationem, "a hollowing out," from excavare, "to hollow out," with its roots of ex-, "out," and cavare, "to hollow."