How to create a Custom Meta Box with Name/Value Admin User Input Fields?

Question

To help you understanding how forms work: They add to the $_POST array by a form fields name argument.

<input type="text" name="foo" value="Fooo!" />

would produce

$_POST (array) =>
    foo => Fooo!

while

<input type="text" name="foo[bar]" value="Bar." />
<input type="text" name="foo[baz]" value="Baz." />

would produce

$_POST (array) =>
    foo => (array) =>
        bar => Bar.
        baz => Baz.

and so on.