Core aeration is a means of alleviating compacted soil. It opens the soil to allow air, water, and fertilizer to penetrate and roots to grow. The aerating holes also provide an entry way for seed to germinate and grow. The plugs can be left on the lawn to decompose. Aeration should be done on moist soil.
Seeding will help to thicken up your turf, improve the overall quality, and helps to minimize weeds.
Take a look at our publication on overseeding for more information http://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/HG102%20La...