The variable initialization allows you to either declare a variable and give it a value or give a value to an already existing variable. Second, the condition tells the program that while the conditional expression is true the loop should continue to repeat itself. The variable update section is the easiest way for a for loop to handle changing of the variable. It is possible to do things like x++, x = x + 10, or even x = random ( 5 ), and if you really wanted to, you could call other functions that do nothing to the variable but still have a useful effect on the code. Notice that a semicolon separates each of these sections, that is important. Also note that every single one of the sections may be empty, though the semicolons still have to be there. If the condition is empty, it is evaluated as true and the loop will repeat until something else stops it.
Example: