What type of materials decompose easily?

Materials such as organic matter (e.g. food scraps, paper, cardboard) and natural fibers (e.g. cotton, wool) decompose easily because they can be broken down by microorganisms into simpler compounds. These materials can be composted to return nutrients back to the soil. Materials that are biodegradable and not heavily processed tend to decompose more easily than synthetic materials such as plastics and metals.