One important concept comes up again and again in the engineering process; it's called iteration. Iteration is a procedure in which you repeat a sequence of steps, each time coming closer to your goal. While it would be nice to do everything once and have a perfect design, there are actually some pretty good reasons why iteration is the norm. We will be iterating our description of the engineering process (see, we can't even describe the process without iterating), and by the end of this document you should have a good understanding of why iteration is a normal and in fact desirable part of engineering design