title: What are Jupyter Notebook checkpoint files for?
body: <p>Besides the original Jupyter Notebook file (<code>.ipynb</code> file), sometimes I get a checkpoint <code>.ipynb</code> file which seems to be directly linked to the original <code>.ipynb</code> file.</p>
  
  <p>What's the purpose of these checkpoint files?</p>
  
  <p>And what causes them to be generated (sometimes I get this sort of checkpoint file, and sometimes I don't)?</p>