title: Where does the TODO convention come from?
body: <p>I suspect this question has been asked before, but it's not easy to Google for. </p>
  
  <p>I am a fairly new coder and I see a lot of code, in a lot of different languages, with comments beginning "TODO". </p>
  
  <p>Questions: </p>
  
  <ul>
  <li>Is there a practical reason why people write TODO in all these different languages, or is it merely a convention?</li>
  <li>If the latter, where did the convention come from?</li>
  </ul>
  
  <p>I can see why it's useful to be able to grep for TODO, I'm just curious about the history behind it. </p>