Operators and Expressins.

You can now assign data to variables, and you can even investigate and change the data type of a variable. A programming language isn't very useful,though,unless you can manipulate the data you can store. Operators are symbols that enable you to use one or more values to produce a new value. A value that is operated on by an operator is referred to as an operand.

An operator is a symbol or series of symbols that, when used in conjunction with values,performs an action and usually produces a new value.

An operand is a value used in conjunction with an operator .There are usually tow operands to one operator.

Let's combine two operands with an operator to produce anew value:
4+5

 4 and 5 are operands and are operated on by the addition operator(+)  to produce 9. Operators almost always sit between two operands. although you will see few exception.

There are five kinds of arithmetic operator.

+   Addition,
-    Subtraction,
/   Division,
*  Multiplication,
%  Modulus,