parameters to method are list of objects that need to be passed into the method that is being called (the objects that are passed in from the calling object are usually referred to as argumentsthese objects are used by the method to perform whatever behavior or task it is meant to do returned values are the results of that task we've stretched our "comparing apples and orangesexample into basic (if farfetchedinventory application let' stretch it little further and see if it breaks one action that can be associated with oranges is the pick action if you think about implementationpick would place the orange in basket by updating the basket attribute of the orangeand by adding the orange to the oranges list on the basket sopick needs to know what basket it is dealing with we do this by giving the pick method basket parameter since our fruit farmer also sells juicewe can add squeeze method to orange when squeezedsqueeze might return the amount of juice retrievedwhile also removing the orange from the basket it was in basket can have sell action when basket is soldour inventory system might update some data on as-yet unspecified objects for accounting and profit calculations alternativelyour basket of oranges might go bad before we can sell themso we add discard method let' add these methods to our diagramorange basket +weightfloat +locationstring +orchardstring +orangeslist +date_pickeddate +sell(customer:customer+basketbasket +discard(+pick(basket:basket +squeeze()amount_of_juice go in adding models and methods to individual objects allows us to create system of interacting objects each object in the system is member of certain class these classes specify what types of data the object can hold and what methods can be invoked on it the data in each object can be in different state from other objects of the same classand each object may react to method calls differently because of the differences in state object-oriented analysis and design is all about figuring out what those objects are and how they should interact the next section describes principles that can be used to make those interactions as simple and intuitive as possible [