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.
A class is an element in object oriented programming that aggregates attributes(fields) - which can be public accessible or not - and methods(functions) - which also can be public or private and usually writes/reads those attributes. so you can have a class like Array with a public attribute lengthand a public method sort().