Classification is grouping of similar process, substance, things together. Classification of diseases is a system in which the patient or disease is divided according to determined criteria. Benefits of the classification systems are to give diseases an international common language, to give an idea in patient management, to provide ease of evaluation in scientific studies and to contribute to the accuracy and reliability of records. In addition, the classification is intended to guide the clinician in evaluating the diagnosis, treatment and prognosis of diseases. Classifications must be reliable, valid, quantitative and objective. A good classification for cerebral palsy (CP) should give an idea on the etiology, be clinically evaluable, objective, and reproducible, help in treatment, and provide information about longterm results. Each classification system should be evaluated according to its positive and negative aspects. Currently, it is not possible to evaluate patients with CP with a single classification due to its wide etiological causes and clinical heterogeneity. Several classification systems have been defined for different usage purposes. Classifications based on functional assessment are used more frequently, as they guide the management of patients with CP. In this review, the development of classification systems in CP and current classification systems are summarized.