title: On Android, what's the difference between running processes and cached background processes?
body: <p>On Android, when I look into "Setting" -> "App", under the tab "running", I can see the memory is cut into to parts: "used memory" and "memory free", also the applications are either put into "used memory", or "memory free". The applications in "memory free" part are noted as "cached background process".</p>
  
  <p>So, what are "cached background processes"? They are still in memory, rather than switched to "disk" (as desktops/laptops do), right? When the user tab one of these "cached background processes", it would be displayed immediately as it is still in memory, just like a running process, right?</p>
  
  <p>What does Android do when it "cache" an application?</p>