title: What is the effect of git commit without the -a option?
body: <p>What is the difference between these two commands?</p>
  
  <pre><code>git commit -m "added a new page"
  </code></pre>
  
  <p>and</p>
  
  <pre><code>git commit -a -m "added a new page"
  </code></pre>
  
  <p>I know that the -a option will stage files that have been modified and deleted, but then what does running it without the -a mean?</p>