This category is for object-oriented languages that are class-based: class-based object-oriented languages, OO with classes.Class-based object-oriented languages are OO with classes. Instances of objects are made by inheriting a master class. The original one was Simula.
This category is for prototype-based languages: classless object-oriented languages, OO without classes.Prototype-based languages are classless object-oriented languages, OO without classes. Instances of objects are made by cloning other instances. Usually, these languages have only one data structure, the associative array. Such languages are very flexible during runtime, and far simpler than class-based languages. The original one was Self.