title: How to make a sticky div with a stopper
body: <p>someone can tell me how this effect is called when I go down on a web page and there is a box that at first was in the middle of the page but on the way down is stuck to the side of the content and also follow you to the bottom the page. i see this on facebook and many website. I know not a 'Div' because these remain fixed</p>
  
  <p>Sorry I forget to wrote they move when only the top of page touches them</p>