How do erosion and deposition work together to form sand dunes?

Waves cause erosion along coastlines and deposit sand away from the shore.
Erosion occurs as surface water carries sediment and the sediment is deposited near oceans and lakes.
Glaciers cause erosion through the movement of large chunks of ice, which are deposited and form depressions.
Erosion occurs through deflation, and sand that was picked up is deposited against an obstruction.