Colorectal carcinoma represents one of the most prevalent malignancies worldwide, with rising incidence across diverse populations owing to modernisation, lifestyle, dietary, and genetic factors. This chapter provides a comprehensive overview of rectal cancer and anal cancer, encompassing biology, staging, pathology, and clinical management. Prognostic determinants are highlighted, alongside the role of biomarkers guiding therapy. Etiological insights emphasize the interplay of sporadic, hereditary, and inflammatory pathways, with syndromes such as FAP and Lynch syndrome underscoring genetic predisposition. Special attention is given to young-onset colorectal cancers, their risk factors, and molecular pathways. Pathological subtypes, prognostic markers, and anatomical considerations—including blood supply, lymphatic drainage, and metastatic patterns—are detailed to inform decision-making.Various treatment strategies are discussed as applicable stage-wise along with adjunctive therapies, palliation, and evolving evidence from landmark trials are examined to contextualize current practice. Screening protocols for average- and high-risk populations are outlined, reinforcing the importance of early detection. Collectively, the chapter integrates epidemiology, biology, clinical features, and therapeutic advances to provide a holistic understanding of rectal and anal cancer management.