Science generates knowledge by means of new discoveries that are often met with disbelief at first, but such knowledge eventually becomes widespread and common. Every school-age child knows the earth revolves around the sun, although this knowledge was rejected when it was first discovered. Most people have a basic understanding of natural processes such as how moisture evaporates then condenses and falls as rain or how oxygen travels through the body in the bloodstream. Science is the reason for the ever-increasing understanding that people have about the world around them.