What is the difference between using a relative URL and an absolute URL in a header redirect in PHP?

When using a header redirect in PHP, it is important to specify the correct URL format to ensure the redirect works as expected. An absolute URL includes the full path to the destination page, including the protocol (http:// or https://), domain, and file path. A relative URL, on the other hand, only includes the file path relative to the current page. Using an absolute URL is recommended for redirects to external pages or when the exact destination path is known, while a relative URL is useful for redirects within the same domain.

// Using an absolute URL for the header redirect
header("Location: https://www.example.com/newpage.php");
exit;

// Using a relative URL for the header redirect
header("Location: newpage.php");
exit;