Self-heal is a term used to describe something that can repair or heal itself without the aid of external sources. There are many synonyms that can be used to describe self-healing, including self-repair, self-regenerate, self-renew, self-mend, and self-restoration. Other words used to describe self-healing processes include self-sustaining, self-maintaining, self-preservation, and self-replenishing. The concept of self-healing is often applied to living organisms, such as plants and animals, as well as materials, such as plastics and metals. The use of self-healing materials in products and structures can reduce maintenance and repair costs, as well as environmental impact.