Throw distance is measured in feet or inches between the projector lens and your screen. For any projector or projector lens, it falls into one of four categories. As the name implies, a standard throw is the most common, needing roughly 10 feet to the screen for a 90-inch image (measured diagonally), give or take a couple of feet depending on the lens. A long throw lets you put the projector much farther away for the same size screen. A short throw lets you position the projector closer than the range for standard throw, which is absolutely necessary in a tight space and actually helpful for a backyard-movie night. That may seem counterintuitive, but if everyone is sitting behind the projector, rather than between the projector and screen, no one can cast shadows when they stand up mid-movie to get another skewer of shrimp from the barbie. Last, ultra short throws, or USTs, let you put the projector just inches away for the same image size. However, these are best avoided for outdoors, in part because they are finicky about being positioned "just so" relative to the screen, which adds to setup time. They also require a much flatter screen than longer throws, and a screen material with absolutely no tendency to move from a wind gust. Even a slight deviation from perfectly flat will distort the image.