Plastic surgery is a surgical specialty involving the restoration, reconstruction or alteration of the human body. It can be divided into two main categories: reconstructive surgery and cosmetic surgery. Reconstructive surgery includes craniofacial surgery, hand surgery, microsurgery, and the treatment of burns. While reconstructive surgery aims to reconstruct a part of the body or improve its functioning, cosmetic (or aesthetic) surgery aims at improving the appearance of it. Comprehensive definition of plastic surgery has never been established, because it no distinct anatomical object and thus overlaps with practically all other surgical specialties. An essential feature of plastic surgery is that it involves treatment of conditions that require or may require tissue relocation skills.