A subclass is class that in the current scope of discussion is below another class in the inheritance hierarchy. In a more strict definition a subclass is a class that is derived from another class or classes. Many languages have a base Object class all classes in these languages are technically subclasses.
|Techniques: Abstraction | Aggregation versus Composition | Association versus Dependency | Coupling | Encapsulation | Information hiding | Inheritance | Multiple Inheritance | Overloading | Polymorphism
Features: Abstract class | Class versus Object | Component versus Module | Instance | Interface | Method | Package versus Namespace | Superclass | Subclass