Cephalexin is an antibiotic belonging to the cephalosporin class, used to treat a variety of bacterial infections. It works by inhibiting the synthesis of bacterial cell walls, leading to cell rupture and death. Cephalexin is particularly effective against gram-positive bacteria, including Streptococcus and Staphylococcus, making it useful for treating skin infections, respiratory tract infections, urinary tract infections, and bone infections.