Foot traffic, heavy clay soil, and mowing over the years all compact the soil underneath your lawn. Compacted soil makes it harder for water, air, and nutrients to reach the roots — even a lawn that gets fertilized regularly can struggle if the soil underneath is too dense.
Core aeration pulls small plugs of soil out of the lawn, relieving that compaction and giving roots room to grow deeper and stronger. Deeper roots mean better drought tolerance and a lawn that bounces back faster from stress.
For cool-season lawns, fall is generally the best time to aerate, since it lines up with their peak growing period. For warm-season lawns, late spring to early summer works better.
If your lawn feels hard underfoot, water tends to pool or run off instead of soaking in, or growth has been thinning despite regular care, it's worth having it checked for compaction.