The Boolean Expression is an expression that 
evaluates to be either true or false.

If the Boolean Expression is true the code
associated with it will be executed.  

If the Boolean Expression is false, the code
associated with the else will be executed instead.

Example:


if (x == 7)
{
   printf ("x equals 7\n");
   printf ("seven is a lucky number.\n");
}
else
   printf ("x does not equal 7\n");


In the example above, the Boolean Expression is:

(x == 7)