Postoperative spinal infections (PSIs) present significant challenges in spinal surgery, leading to considerable patient morbidity, extended hospital stays, and increased healthcare costs. This chapter provides a comprehensive review of PSIs, focusing on infection classification, risk factors, and management strategies. It distinguishes between superficial and deep infections, with particular attention to the complexities introduced by spinal instrumentation, which increases susceptibility to bacterial colonization. Risk factors like prolonged operative time, use of hardware, and patient comorbidities such as obesity and diabetes are explored, alongside prevention strategies that include patient optimization and the use of prophylactic antibiotics. Diagnostic methods, primarily using MRI, facilitate early detection and accurate identification of infection depth. Treatment approaches are tailored based on infection severity and instrumentation involvement, ranging from conservative antibiotic therapy to surgical intervention. Through a multidisciplinary approach, this chapter underscores the importance of timely diagnosis and personalized treatment to enhance patient outcomes in spinal surgery.