Why do they give us a link for this task?

Tell us what’s happening:

I don’t need help with this task I was just wondering why this gives us the link to add bootstrap. Is this something we are going to learn how to code from scratch? Should we go in depth learning bootstrap? I still don’t understand the concept after looking it up.In basic yet in depth terms can someone please define a web framework? I get that they enable us to make apps having to add specifications to fit mobile screen etc. But that’s about as far as my understanding goes.

Your code so far

<link href="https://fonts.googleapis.com/css?family=Lobster" rel="stylesheet" type="text/css">
<style>
  .red-text {
    color: red;
  }

  h2 {
    font-family: Lobster, Monospace;
  }

  p {
    font-size: 16px;
    font-family: Monospace;
  }

  .thick-green-border {
    border-color: green;
    border-width: 10px;
    border-style: solid;
    border-radius: 50%;
  }

  .smaller-image {
    width: 100px;
  }
</style>

<div class="container-fluid">
  <h2 class="red-text">CatPhotoApp</h2>

  <p>Click here for <a href="#">cat photos</a>.</p>

  <a href="#"><img class="smaller-image thick-green-border" src="https://bit.ly/fcc-relaxing-cat" alt="A cute orange cat lying on its back. "></a>
  
 <img class="img-responsive" src= "https://bit.ly/fcc-running-cats">

  <p>Things cats love:</p>
  <ul>
    <li>cat nip</li>
    <li>laser pointers</li>
    <li>lasagna</li>
  </ul>
  <p>Top 3 things cats hate:</p>
  <ol>
    <li>flea treatment</li>
    <li>thunder</li>
    <li>other cats</li>
  </ol>
  <form action="/submit-cat-photo">
    <label><input type="radio" name="indoor-outdoor"> Indoor</label>
    <label><input type="radio" name="indoor-outdoor"> Outdoor</label>
    <label><input type="checkbox" name="personality"> Loving</label>
    <label><input type="checkbox" name="personality"> Lazy</label>
    <label><input type="checkbox" name="personality"> Crazy</label>
    <input type="text" placeholder="cat photo URL" required>
    <button type="submit">Submit</button>
  </form>
</div>

Your browser information:

Your Browser User Agent is: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36.

Link to the challenge:
https://www.freecodecamp.org/challenges/make-images-mobile-responsive

a framework is essentially a set of generic reusable code that allows you to develop faster by writing less code