Any loose, usually organic material placed over the soil – such as ground bark, sawdust, straw or leaves – is a mulch. The process of applying such materials is called mulching. A mulch can serve various functions. It may reduce evaporation of moisture from soil, reduce evaporation of moisture from soil, reduce or prevent weed growth, insulate soil from extreme or rapid changes of temperature, prevent mud from splashing onto foliage and other surfaces, protect falling fruit from injury, or make a garden bed look tidy.