Diverticulitis is defined as inflammation around a diverticulum, generally in the colon. Accurate classification of diverticulitis is important as there is a wide spectrum of diverticular disease. Classification allows clinicians to follow appropriate treatment protocols and is essential for studying outcomes and treatments of diverticulitis. Classifying and reclassifying diverticulitis has been an ongoing process over the last 50 years. The original Hinchey classification was published in 1978. It has undergone multiple modifications since that time, and the modified Hinchey classification is the most widely accepted classification schema for acute diverticulitis. Despite its widespread utilization, it fails to categorize several phenotypes of diverticulitis and in particular fails to classify chronic diverticulitis and complications that can arise from this chronic inflammatory process. To address the Hinchey classification shortcomings, there have been an additional ten classification systems that have been published. Despite the plethora of classification systems, however, there are few studies that directly compare the efficacy of these various systems. Thus, rather than focusing on the value of a particular classification system, it is best to explore the major decision-making points that existing classification systems have in common. In particular, for acute disease, the key decision point is whether there is a complicated or noncomplicated disease based on the presence or absence of an abscess, fistula, or free intraperitoneal contamination. For chronic disease, the time course of the disease, the impact on the quality of life, and the presence of complications from diverticulitis such as stricture or fistula are the most salient features to determine appropriate therapy.