title: What is a sources JAR?
body: <p>I was recently trying to import a library to use for something I am working on.</p>
  
  <p><a href="https://sites.google.com/site/piotrwendykier/software/jtransforms" rel="noreferrer">https://sites.google.com/site/piotrwendykier/software/jtransforms</a></p>
  
  <p>I was having some difficulty because the JAR that I added to the build path was the "JTransforms-3.0-sources.jar" and not the "JTransforms-3.0.jar".</p>
  
  <p>Now I am sort of scratching my head and just wondering what that first sources.jar was if it didn't have any of the classes that I wanted to use in it.</p>
  
  <p>What is it and what is it for?</p>