Lung cancer staging is a process used to determine the extent of the disease in the body. It helps doctors understand how far the cancer has spread, which is crucial for deciding the best treatment options. The most common system used for staging is the TNM system, which evaluates the size of the tumor (T), whether cancer has spread to nearby lymph nodes (N), and if there are any distant metastases (M). Staging is typically classified into four main stages, ranging from Stage 0 (in situ) to Stage IV (advanced cancer). Each stage indicates the severity and spread of the disease, guiding treatment decisions and helping predict patient outcomes. Accurate staging is essential for effective management of lung cancer.