programming easier making classes work together to make complex programming easier so in our introduction to object-oriented programming (oop)we found out summary of introduction that objects hold attributes (dataand methods (functions that act on datato oop together in one related entity realizations of an object are called instances the template or form for an object is called classso realizations are instances of class in pythonthe class statement defines the template for object instances in the class statementinstances of the class are called self once real instance of the class is createdthe instance (objectname itself is "substitutedin for self but so whatit seems like classes are just different way of organizing data and functionsinstead of putting them in libraries (or modules)you put them in class if you're thinking that this isn' that big of deali would agree that it isn' big dealif all you do in program is write single class with single instance of that classin that caseoop does not buy you very much the real power of ooprathercomes when objects are used in conjunction with other classes by properly designing your set of classesthe object-oriented structure can make your code much simpler to write and understandeasier to debugand less prone to error in the remaining sections of the we'll look at two case studies illustrating the use of oop in this manner the first case study extends our book and article classes by examining the more general program of how to create bibliography in the second case studywe consider how to create class for geosciences work that "managesa surface domain case study the bibliography example the book and article classes we wrote earlier manage information related to books and articles in this case studywe make use of book and article to help us implement one common use of book and article informationthe creation of bibliography in particularwe'll write bibliography class that will manage bibliographygiven instances of book and article objects structuring the bibliography class since bibliography consists of list of (usually formattedbook and article entrieswe will want our bibliography class to contain such list thus