DIN stands for "Deutsches Institut für Normung," which is a German organization that sets standards for all kinds of products, including car stereos. DIN size refers to the size of the stereos chassis, and car stereos come in two standard sizes: single-DIN and double-DIN. The main difference between single-DIN and double-DIN car stereos is their size. Single-DIN stereos are two inches tall and seven inches wide, while double-DIN stereos are four inches tall and seven inches wide. Single-DIN stereos have a minimal interface, giving them an easier control panel for some users. With fewer features to offer, single-DIN stereos are usually lower in price. Double-DIN stereos have more room for controls, so they tend to be easier to use. They also offer more advanced features, such as touchscreens, which are not available in single-DIN stereos. While you cannot install a double-DIN in place of a single-DIN, you can install a single-DIN in place of a double-DIN, though it may be more difficult.