People usually view opaque curtains as the opposite of sheer curtains. When you want to block out all the light, opaque curtains are the best fit. Therefore they are suitable for those rooms you never want to allow any natural light in. Note that the opaque curtains provide more privacy compared to sheer curtains. The latter may not be the best, especially if you live in an area where your house is a stone's throw away from your neighbor's. We love our privacy, and it is necessary to keep those prying eyes off our business. If you want to know which one is the best for you, you can consider the function of the curtains you will get first.