The Fission Theory: This theory proposes that the Moon was once part of the Earth and somehow separated from the Earth early in the history of the solar system.
This provides modular approach to programming. Classes. A class is a concept used in object oriented programming languages such as C++, PHP, and JAVA etc. Apart from holding data, a class is also used to hold functions. An object is an instant of a class. In case of variables, the type is the class whereas the variable is the object.
Class methods are usually used to create instances of that class. For example, [NSString stringWithFormat:@SomeParameter]; returns an NSString instance with the parameter that is sent to it. Hence, because it is a Class method that returns an object of its type, it is also called a convenience method.