Tumor Node Metastasis (TNM) is a system used by medical professionals to describe the extent of cancer in a patient's body. It classifies cancer based on three key components: the size and extent of the primary tumor (T), the involvement of nearby lymph nodes (N), and the presence of distant metastasis (M). Each component is assigned a number or letter to indicate the severity and spread of the disease. The TNM system helps doctors determine the stage of cancer, which is crucial for planning treatment and predicting outcomes. For example, a higher stage often indicates a more advanced disease, requiring more aggressive treatment options. This standardized approach allows for better communication among healthcare providers and aids in research and clinical trials.