data describes objects let' start with data data typically represents the individual characteristics of certain object class can define specific sets of characteristics that are shared by all objects of that class any specific object can have different data values for the given characteristics for exampleour three oranges on the table (if we haven' eaten anycould each weigh different amount the orange class could then have weight attribute all instances of the orange class have weight attributebut each orange has different value for this attribute attributes don' have to be uniquethoughany two oranges may weigh the same amount as more realistic exampletwo objects representing different customers might have the same value for first name attribute attributes are frequently referred to as members or properties some authors suggest that the terms have different meaningsusually that attributes are settablewhile properties are read-only in pythonthe concept of "read-onlyis rather pointlessso throughout this bookwe'll see the two terms used interchangeably in additionas we'll discuss in when to use object-oriented programmingthe property keyword has special meaning in python for particular kind of attribute orange basket +weight +orchard +date_picked +location go in go in apple barrel +color +weight +size in our fruit inventory applicationthe fruit farmer may want to know what orchard the orange came fromwhen it was pickedand how much it weighs they might also want to keep track of where each basket is stored apples might have color attributeand barrels might come in different sizes some of these properties may also belong to multiple classes (we may want to know when apples are pickedtoo)but for this first examplelet' just add few different attributes to our class diagram[