In Section 1.1.2, it was pointed out that four levels of design complexity can be identified. In order of increasing complexity, they are the component level, the product level, the system level, and the community level. It was also pointed out that system-level and community-level design projects have essentially identical design procedures and engineering aspects, and that component-level and product-level designs are quite similar to each other. For brevity, we have generally referred to the two higher design levels as systems; we have referred to the two lower design levels randomly as devices, components, or products. In all likelihood, you have probably thought about devices or products while studying the previous chapters. This is a natural thing to do; it is easier to comprehend simple cases than the more complex ones.