Staging is the process of determining the extent and spread of a disease, most commonly cancer, within the body. It helps healthcare providers assess how advanced the condition is and guides treatment planning and prognosis. Cancer staging typically considers the size of the tumor, involvement of nearby lymph nodes, and presence of distant metastasis—commonly summarized using the TNM (Tumor, Node, Metastasis) system. Accurate staging is essential for selecting appropriate therapies and comparing outcomes across patients and clinical studies.