Learn HTML by Building a Cat Photo App - Step 1 - V8dP3M9GZyHQllTLWlh8t

Tell us what’s happening:
Describe your issue in detail here.

  **Your code so far**
<html>
<body>
  <CatPhotoApp>.Hello World</CatPhotoApp>.
</body>
</html>

I do not understand why the html is wrong. Can anyone help me?

  **Your browser information:**

User Agent is: Mozilla/5.0 (iPhone; CPU iPhone OS 15_4_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.4 Mobile/15E148 Safari/604.1

Challenge: Learn HTML by Building a Cat Photo App - Step 1

Link to the challenge:

Your head elment is missing.
There is nothing like CatPhotoApp element.
Follow the simple instructions you have there.