title: What is the difference between a physical width and CSS width in pixels?
body: <p>I am currently using Photoshop, to create a series of Wireframes, for a future website design.  Naturally, I will be wanting the website to be responsive; which will be aided by Bootstrap.</p>
  
  <p>I will be working with the Smartphone screen sizes first and then scaling up the screen sizes accordingly.</p>
  
  <p>According to Bootstrap, Smartphones generally range between 480px to 767px.  Admittedly, the later being more Tablet based.</p>
  
  <p>Where I am a little uncertain, is that when I check out the phone specifications, the physical screen widths are much greater than the CSS widths.</p>
  
  <p>Let's take the HTC One phone.  The CSS screen dimensions are 360px by 640px whilst the physical screen width is 1080px by 1920px.  Referring to the width, this would suggest the physical screen width is 3 times width than the CSS width of the website.  After looking at a few websites, on the HTC One, the websites' widths are certainly not 3 times smaller than the actually screen's physical width.  </p>
  
  <p>I am just wondering if I have misunderstood something here.  For example, pixels may be a different size when measuring physical screens for example.</p>