Why is only biodegradable material added to a compost heap?

Only biodegradable material is added to a compost heap because these materials can break down naturally through microbial activity, converting them into nutrient-rich compost. Non-biodegradable materials, such as plastics or metals, do not decompose and can contaminate the compost, reducing its quality and harming the environment. Additionally, using only biodegradable materials helps maintain a balanced ecosystem within the compost, promoting effective decomposition and minimizing odors and pests.