A wound is an injury that breaks the skin or other external surface. There are two main types of wounds - open wounds caused by cuts, lacerations, abrasions, punctures or gunshots, and closed wounds like bruises, blood tumors or crush injuries. Wound closure can be primary, where the wound is immediately sealed, secondary where it closes on its own over time, or delayed primary where it is closed after repeated cleaning. The phases of healing are inflammatory, proliferative and maturational, involving processes like blood clotting, new cell and blood vessel growth, and scar formation. Factors that can affect healing include infection, nutrition, steroids, mechanical forces, age, radiation, and diseases like