title: Add text to .jpg/png/gif
body: <p>I heard there is some way, to add additional hidden text inside code of the image file (like jpg/png/gif).</p>
  
  <p>If we open this image in windows, will be shown a picture, but if we open it by some text-editor (like notepad++), we will see our hidden text.</p>
  
  <p>How is this method called? What can you say about it?</p>
  
  <p>Thanks.</p>