title: Single PNG file for multiple icons
body: <p>I have noticed that Facebook and Instagram uses the same way of displaying icons found on the site, which is to add into a single PNG file all the icons and make the styling based on their position?</p>
  
  <p>Please have a look on the <a href="https://www.instagram.com/static/bundles/sprite_core_2x.png/2f351c15a81e.png" rel="nofollow noreferrer">Instagram way of doing it</a>.</p>
  
  <p>I understand that in this way, the client will receive only a single image which will be cached and the user performance will increase. But how do they do it?</p>
  
  <p>Thank you for your time!</p>