Paving over an area is a process that involves resurfacing, retopping, and retarring. Resurfacing is the process of laying down a new layer of material on top of the existing surface. Retopping is the process of adding a new layer of asphalt or concrete to the existing surface. Finally, retarring is the process of applying a tar-based sealant to the surface to protect it from the elements. All three processes are necessary for a successful paving job.