Cancer staging is a process used to determine the extent of cancer in a patient's body. It helps doctors understand how far the disease has spread, which is crucial for planning treatment. The most common system 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 distant metastases (M). Staging is typically classified into stages ranging from 0 to IV. Stage 0 indicates a localized cancer that has not spread, while Stage IV signifies advanced cancer that has spread to other organs. Accurate staging is essential for predicting outcomes and choosing the most effective treatment options.