WHILE LOOPS

while loops are somewhat similar to if statements in that they evaluate an expression to determine if that express is True or False.  if statements will evaluate an expression a single time, and if the expression is True, the if statement will execute a code block.  

On the other hand, while loops will evaluate an expression, and if the expression is True, the while loop will execute a code block and then go back and start over.  If will evaluate the expression again, and if the expression is still True, it will execute the code block again.  It will do this until either the expression is no longer True, or until something in the code block says to STOP!

The most basic while loop is one that will execute forever.  In fact, that's the point of it -- it will keep going until someone explicitly stops the program.  It is written as follows:

Because the expression "True" always evaluates to True, this code block will loop over and over forever until the program is stopped by the user.