Practically speaking, aeration is the process of mechanically removing small plugs of thatch and soil from the lawn to improve natural air flow. It's commonly called "core aeration" in the lawn service industry, and you may have heard of it referred to as soil cultivation (coring, spiking and slicing). Most homeowners simply call it aeration.
Benefits of aeration:
Most beneficial time to aerate and over seed in our area is September and October