What is Mulch?

Mulch is used to retain moisture in the soil, suppress weeds, keep the soil cool, prevent frost heaving in winter, and make the garden bed look more attractive. Organic mulches also help improve the soil’s structure, drainage, and nutrient-holding capacity as they decompose.

https://www.goodhousekeeping.com/home/gardening/a20706549/how-to-mulch-your-garden/#:~:text=There%20are%20two%20basic%20kinds,and%20geotextiles%20(landscape%20fabrics).