Every variable has
   1) name
   2) type
   3) value
   4) location

The type can be any of
   a) int
   b) double
   c) boolean
   d) String

The types int, double, boolean are called "primitive types".

The type String is called a "reference type".

The value for a variable can come from
   1) a literal
   2) an expression
   3) program input

An "expression" is the word we use for what algebra calls a "formula".
Expressions are made up of variables, literals, and operators.

The most basic operators are +, -, *, /, %.
The meaning of each operator depends on the type of its operands!

When we write
   x + y
we call + the operator, and x, y are the operands. What
the operator + does depends on the types of the x and y!
And for some types of x and y, x + y is an error (what
would be an example?).

Question: In the following expression, what are the
operands of the * operator?
   x * (3 + y)

Question: Is the following a true or false statement?
  "You cannot give the + operator a boolean operand."