title: Understanding Flask request object
body: <p>I would like to understand how the <code>request</code> object from <code>Flask</code> works. Specifically, by looking at the code below, taken from <a href="https://techtutorialsx.com/2017/01/07/flask-parsing-json-data/" rel="nofollow noreferrer">here</a>. 
  <a href="https://i.stack.imgur.com/EOMzG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EOMzG.png" alt="enter image description here"></a></p>
  
  <p>My question is: where is the link between the <code>request</code>object, and the actual request that is made?</p>
  
  <p>Put another way, how does <code>request.is_json</code> knows which data it should point to (the data sent through the request). </p>
  
  <p>Thanks for any help!</p>