2.  Class diagrams show the classes of the system, their interrelationships (including inheritance, aggregation, and association), and the operations and attributes of the classes.  Class diagrams are used for a wide variety of purposes, including both conceptual/domain modeling and detailed design modeling.

3. 1. Class 2. Attribute 3. Methods (Operations) 4. Generalization 5. Association 6. Multiplicity 7. Aggregation

4.  An object is any person, place, thing, concept, event, screen, or report applicable to your system.  A class is a representation of an object and, in many ways, it is simply a template from which objects are created.  Although thousands of students attend the university, you would only model one class, called Student, which would represent the entire collection of students.

5.  An attribute of a class represents a characteristic of a class.  Characteristics of interest of a passenger, for example, are name and age.

6.  The operations describe how a class can interact with data.  All classes have different access levels depending on the access modifier (visibility).  Here are the following access levels with their corresponding symbols:  Public (+)  Private (-)  Protected (#)  Static (underlined)

7.  Terms such as superclass, subclass, or inheritance come to mind when thinking about the object-oriented approach.  Generalization is the process of extracting shared characteristics from two or more classes, and combining them into a generalized superclass. Shared characteristics can be attributes, associations, or methods.

9.  An association represents a relationship between two classes.  An association indicates that objects of one class have a relationship with objects of another class, in which this connection has a specifically defined meaning.

10.  A multiplicity allows for statements about the number of objects that are involved in an association.

11.  An aggregation is a special case of an association meaning "consists of“