How many tags are needed to create an HTML page…

The minimum tags are:

<!DOCTYPE html>: Declares the document type. Technically, it is not a tag but a declaration, but it is required.
<html>: The root element of the page.
<body>: Contains the visible content of the page.

Strictly speaking, you can create an empty *.html file without content, but it will not be a valid HTML page for viewing.

To display something, at least one additional tag inside <body> is needed, for example:

<!-- Main structure -->
<!DOCTYPE html>
<html>
<body>
  <p>Hello, world!</p>
</body>
</html>

Also, for proper encoding and basic page info, a <head> element containing metadata is necessary:

<!-- Extended structure with head -->
<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8"> <!-- Specifies encoding -->
  <title>My page</title> <!-- Page title in browser -->
</head>
<body>
  <h1>Header</h1>
  <p>Some text.</p>
</body>
</html>

Thus, for a functional and valid HTML page, at least 5 elements/declarations are needed: <!DOCTYPE html>, <html>, <head>, <title>, <body> (although <title> and <head> content are technically optional for display, they are crucial for SEO and user convenience).

But for a minimal structure that a browser parser can process, three mentioned at the start are enough.

How many tags are needed to create an HTML page?