Surgical site infection (SSI) occurs when bacteria enter the surgical wound during or after a procedure. There are three types - superficial, deep, and organ/space - depending on the infected tissue layers. Risk factors include patient health issues, emergency procedures, and poor surgical technique. Symptoms may include wound drainage or pain. Treatment involves antibiotics, wound drainage, and sometimes reoperation. Prevention strategies focus on proper antibiotic use, maintaining sterile technique, controlling patient temperature and blood sugar, and following bundles of best practices like the "7 S Bundle". SSIs remain a challenge despite preventive efforts.