iteration
    A single pass through the loop.

loop test
    The testings of a Boolean condition which must be true in order for the loop to execute again.

termination condition
    The Boolean condition that causes a loop to be exited.

count-controlled loop
    A loop that executes a specified number of times.
 
event-controlled loop
    A loop that executes until something happens--ie an event occurs--within the loop to cause the
    termination condition to be true.

sentinel-controlled loop
    An event-controlled loop in which a special data value, called the "sentinel", when read in, signals
    the program that no more data should be read in.

end-of-file controlled loop
    A loop which inputs values and terminates when the end of file is reached.  The details of how this actually
    works is languge dependent.

nested loop
    A loop the occurs within another loop.