Core Aeration removes soil plugs from your lawn. It helps reduce soil compaction, thatch, and improves drainage. Proper core aeration works by allowing air circulation, water, and fertilizer to reach greater depths into the subsoil. After the core aeration has been performed, you will notice that the soil plugs have been left over the serviced area. After a mowing or two they will break down and return nutrients back to the soil.
If seeding is done at the same time, those areas need to be kept moist (not soaked) until the seed germinates and begins to grow.