What are the implications of using absolute paths versus relative paths when defining file paths for uploaded files in PHP?

When defining file paths for uploaded files in PHP, using relative paths can make the code more portable and easier to maintain. However, using absolute paths can provide more security and prevent potential issues with file paths. It is important to carefully consider the implications of each approach based on the specific requirements of the project.

// Using relative path for file upload
$uploadDir = 'uploads/';
$uploadFile = $uploadDir . basename($_FILES['file']['name']);

// Using absolute path for file upload
$uploadDir = '/var/www/html/uploads/';
$uploadFile = $uploadDir . basename($_FILES['file']['name']);