Gas gangrene is a life-threatening infection of subcutaneous tissue and muscle caused by clostridial bacteria such as Clostridium perfringens, which release toxins like alpha toxin that cause tissue necrosis. It is associated with wounds, surgery, or trauma and has a rapid onset of symptoms like pain, swelling, crepitus, and gangrenous changes in the skin. Aggressive surgical debridement and antibiotics such as penicillin are needed for treatment to prevent complications like sepsis, shock, and potential limb loss.