Coring involves the removing of soil plugs called cores .The removal of this soil allows the lawn to breathe, water and nutirents to travel into the soil faster.
Cores can be removed or allowed to dry in the sun and mown over next time you cut your lawn, which will return the soil to the lawn .

 Core Aerate your lawn you will save water as your lawn will hold more water , the plug holes that the corer makes will full with water and this water will move within the soil faster and stay in the soil making for a better grass plant.