The most used Android app in Q4 2015 left phones feeling clean. It is a seductive thing, the app cleaning software market. We all want our phones to be "optimized" and "clean" and smooth running. So, we install apps like CleanMaster, and "clean" our phones of all that detritus that Android leaves lying around. I admit it. Before I knew better, I was taken in by the appeal. I am always tweaking my tech, and it was too tempting to pass up. But, I learned, and I now know better. You don't need CleanMaster, or any other similar program. Google does a great job of keeping Android running, no matter what you put it through. Relax. If you really want to do something useful, get rid of the 9,000 emails sitting in your In Box. In Box Zero doesn't cost anything, and you really will have a clean phone.