Ventilation is something that is needed in most buildings whether we're talking about a small shack or a large warehouse or possibly even a skyscraper. Therefore, it is not surprising that fans come in many sizes. There are small fans which cool computer components and there are large, industrial-sized fans which move lots of air through large enclosed areas. However, one of the most interesting things about fans is that they are very similar to propellers and so fans, if we broaden the definition a bit, are not only used for ventilation, but they are also used to move vehicles such as airplanes and boats. For that matter, if we broaden the definition even further, we have windmills. It is for this reason that most of these items are included in the video featured on this page! But even if we stick with a narrow definition of what a fan is and what a fan is not, there is still a remarkable range of types of fans we might see, for instance, in a typical house. Undoubtedly, there is at least one fan in most households and most people own several in one form or another.