Coma is a state of unconsciousness in which a person is unresponsive to external stimuli and unable to be awakened. It is typically caused by severe brain injury, stroke, or other medical conditions that disrupt the normal functioning of the brain. Coma is often considered a medical emergency and requires immediate attention and treatment to prevent further complications. In some cases, a person in a coma may eventually regain consciousness, while in other cases, they may remain in a persistent vegetative state. Research in the field of coma focuses on understanding the underlying causes, improving diagnostic techniques, and developing new treatments to help improve outcomes for patients in comatose states.