Ruby provides a number of built-in classes that are listed below. These are always available and no require statement or other statement is needed to enable them: * Object * Module * Class * Array * Binding * Continuation * Data * Dir * Exception * fatal * NoMemoryError * ScriptError * LoadError * NotImplementedError * SyntaxError * SignalException * Interrupt * StandardError * ArgumentError * IndexError * IOError * EOFError * LocalJumpError * NameError * NoMethodError * RangeError * FloatDomainError * RegexpError * RuntimeError * SecurityError * SystemStackError * SystemCallError * ThreadError * TypeError * ZeroDivisionError * SystemEx