title: How to change image resolution by URL?
body: <p>Let's look at this link: <a href="https://images-eu.ssl-images-amazon.com/images/I/51KyXgRx4cL._SY100_.jpg" rel="nofollow noreferrer">https://images-eu.ssl-images-amazon.com/images/I/51KyXgRx4cL.<em>SY100</em>.jpg</a>. This shows an image with a height of 100px and a resolution of 5kb</p>
  
  <p>You can change the size and also resolution by changing the number before <code>.jpg</code>.</p>
  
  <p>When changing it to e.g. <a href="https://images-eu.ssl-images-amazon.com/images/I/51KyXgRx4cL.SY300.jpg" rel="nofollow noreferrer">https://images-eu.ssl-images-amazon.com/images/I/51KyXgRx4cL.SY300.jpg</a> it has a height of 300px and a resolution of 30kb.</p>
  
  <p>How are they doing it? Are there really hundreds of copies of this single image? Or, is this made by <code>.htaccess</code>? Or are they using complicated web apps? Can I do this for my own server?</p>