Thatch is the dead mat of stems and roots packed between your grass and the soil. A thin layer is normal. Once it passes half an inch it works like a tarp — water runs off, fertilizer sits on top, and roots grow sideways instead of down. We pull that layer out with a power dethatcher, rake it up, and haul it off the same day.
Get a QuotePhoto illustrative of the process, not a specific job site.