What is a Type 4 burn?

Could you please elaborate on what exactly a Type 4 burn is? As someone who is not familiar with the medical terminology related to burns, I am curious to know how severe a Type 4 burn is and what specific characteristics it possesses. Is it a particularly dangerous type of burn, and if so, what kind of treatment is typically required for someone who has suffered such an injury? Additionally, how does a Type 4 burn differ from other types of burns, such as Type 1, Type 2, or Type 3 burns?