Excavators are used in many ways:
Digging of trenches, holes, foundations
Material handling
Brush cutting with hydraulic attachments
Forestry work
Forestry mulching
Demolition
General grading/landscaping
Mining, especially, but not only open-pit mining
River dredging
Driving piles, in conjunction with a pile driver
Drilling shafts for footings and rock blasting, by use of an auger or hydraulic drill attachment
Snow removal with snowplow and snow blower attachments