title: What is the session's "secret" option?
body: <p>I don't know anything about cryptography. I'm wondering what the session secret is.</p>
  
  <p>I see code like this:</p>
  
  <pre><code>app.use(express.session({
    store: mongoStore({
      url: app.set('db-uri')
    }),
    secret: 'topsecret'
  }));
  </code></pre>
  
  <p>What is the secret and should I change it?</p>