the core of the matter

Aeration removes thousands of soil cores from your lawn and deposits them above the thatch layer. The cores are about a half inch in diameter and 2" to 3" long. Thats it. It sounds simple, but as soon as aeration is completed, a lot of good things begin to happen to your lawn - and continue for months after the service is performed. The first immediate benefit is the creation of tiny pockets in your lawn to catch and hold air, water and fertilizer. This is esecially important in heavy soils that tend to be compacted and shed water rather than absorbing it. The next thing that you'll notice is that the soil cores begin to dissolve during rainfall and irrigation. This soil is mixing with the thatch layer and helping it decompose, preventing a thick solid blanket of thatch over the lawn. Then, because the holes are catching water and fertilizer, the grass roots begin to grow towards them, getting fuller and thicker on the way. And since there is extra space, the compacted soil of your lawn begins to loosen, and that means more oxygen reaches the roots and they can grow deeper with out hitting hard soil.