defining classes objectives to appreciate how defining new classes can provide structure for complex program to be able to read and write python class definitions to understand the concept of encapsulation and how it contributes to building modular and maintainable programs to be able to write programs involving simple class definitions to be able to write interactive graphics programs involving novel (programmer designedwidgets quick review of objects in the last three we have developed techniques for structuring the computations of program in the next few we will take look at techniques for structuring the data that our programs use you already know that objects are one important tool for managing complex data so farour programs have made use of objects created from pre-defined classes such as circle in this you will learn how to write your own classes so that you can create novel objects remember back in defined an object as an active data type that knows stuff and can do stuff more preciselyan object consists of collection of related information set of operations to manipulate that information the information is stored inside the object in instance variables the operationscalled methodsare functions that "liveinside the object collectivelythe instance variables and methods are called the attributes of an object