Head should be a child of html

I cant complete this code it is showing that the head tag should be a child of the html tag. But i dont know what that is supposed to mean.
could you please explain to me what child element is supposed to mean???

Your code so far


<!DOCTYPE html>
<html>
<head>
  <title>The best page ever</title>
</head>
<body>
  <h1>The best page ever</h1>
  <p>Cat ipsum dolor sit amet, jump launch to pounce upon little yarn mouse, bare fangs at toy run hide in litter box until treats are fed. Go into a room to decide you didn't want to be in there anyway. I like big cats and i can not lie kitty ipsum dolor sit amet, shed everywhere shed everywhere stretching attack your ankles chase the red dot, hairball run catnip eat the grass sniff. Meow i could pee on this if i had the energy for slap owner's face at 5am until human fills food dish yet scamper. Knock dish off table head butt cant eat out of my own dish scratch the furniture. Make meme, make cute face. Sleep in the bathroom sink chase laser but pee in the shoe. Paw at your fat belly licks your face and eat grass, throw it back up kitty ipsum dolor sit amet, shed everywhere shed everywhere stretching attack your ankles chase the red dot, hairball run catnip eat the grass sniff.</p>
</body>
</html>

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Challenge: Define the Head and Body of an HTML Document

Link to the challenge:

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do you have Firefox? the latest version is 81 so maybe try updating your browser