Colorectal cancers are a common cause of cancer-related mortality in the developed world. Though screening has decreased the incidence of this cancer in older patients, its incidence has increased among men and women under age 50. Adenocarcinomas are generally treated with a combination of surgical resection, systemic therapy, and, in the case of rectal cancers, chemoradiotherapy. Anal squamous cell carcinomas are treated with definitive chemoradiotherapy, with surgical resection reserved for salvage if residual disease is present. Patient survival is significantly higher with localized or locoregional cancers, emphasizing the importance of early detection through screening or investigation of anemia, blood in stool, or rectal bleeding. Several hereditary syndromes with unique surgical treatments are associated with colorectal cancer; thus a thorough family history and genetic testing is an important part of the preoperative evaluation. Surgical techniques have advanced for colorectal cancer, especially the increased use of minimally invasive surgical platforms. Similarly, advances in systemic therapy have improved survival for metastatic patients and allowing more of them to be surgical candidates. Understanding the screening, diagnosis, surgical treatment, and nonsurgical therapies used for these common cancers is essential for any surgical oncologist or colorectal surgeon.