title: Observable Versus Callback
body: <p>I have been doing javascript for a while now. However, I am fairly new to Angular 2, so I know almost nothing about Observables. When I was reading the descriptions of Observables they sounded a lot like the callbacks that I already knew. When I asked Google there were comparisons between callbacks and promises, and there were comparisons between promises and observables. However, I was unable to find any comparison between callback and Observables.</p>
  
  <p>What is the difference between callbacks and observables?</p>