Every HTML document should end with the </html>
tag. This tag signifies the end of the HTML document. Here is a simple structure of a complete HTML document:
<!DOCTYPE html>
<html>
<head>
<title>Document Title</title>
</head>
<body>
<h1>Hello, World!</h1>
</body>
</html>
In this structure, the </html>
tag at the end is necessary to properly close the HTML document.