title: How do dp, dip, dpi, ppi, pixels and inches relate?
body: <p>I was reading <a href="https://stackoverflow.com/questions/2025282/difference-of-px-dp-dip-and-sp-in-android">dp, dip, px, sp measurements</a>, but I still have some questions about dp/dpi vs ppi vs px vs inch. I am not able to compare them... is an inch the largest? </p>
  
  <p>They say 160 dpi means 160 pixels per one inch. Does that mean 1 inch contains 160 pixels? </p>
  
  <p>They also say 1 pixel on a 160 dpi screen = 1 dp. Does that mean 1 pixel and 1 dp are equal?</p>
  
  <p>And lastly, why should we use dp instead of px? I understand that it is ideal, but <em>why</em>?</p>