title: What is Over-Fetching or Under-fetching?
body: <p>I've been playing sometimes with graphQL. Before graphQL, we normally use REST API. Many developers said that graphQL fixes some problems of the REST. (e.g. over-fetching &amp; under-fetching). I confuses with this terms.</p>
  
  <p>Can somebody explain what is over and under fetching in this context? </p>
  
  <p>Thanks,</p>