- class & instance data values
  - store information about self
  - often altered by messages
- all instances of same class
  - possess same set of data values
  - content may vary
- class data value
  - information shared by all instances
  - collective information about the instances
  - an instance can access data vals of the class to which it belongs
- data member synonym for data val
- representing class data val as instance data val wastes space
- types of data vals
  - variable: can change over time
  - constant
    - cannot change over time
    - keyword frozen on UML diagrams
- data val summary
  - class var
  - class const
  - instance var
  - instance const

Quick Check:
1. The values of a variable may change throughout the program, while a constant's value is fixed to its intial value, which is assigned upon declaration.
2. 
    ______________
   |              |
   |  p : Person  |
   |  ----------  |
   |______________|
   |              |
   |  name        |
   |  __________  |
   | |          | |
   | | Michelle | |
   | |__________| |
   |              |
   |  age         |
   |  __________  |
   | |          | |
   | |    21    | |
   | |__________| |
   |              |
   |  gender      |
   |  __________  |
   | |          | |
   | |  female  | |
   | |__________| |
   |______________|