How can PHP be integrated with WordPress for form handling and redirection?

To integrate PHP with WordPress for form handling and redirection, you can create a custom PHP file within your WordPress theme directory. This file can handle form submissions, process the data, and redirect users to a specific page based on the form input.

```php
<?php
// Template Name: Custom Form Handler

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Process form data here
    
    // Redirect to a specific page
    wp_redirect( home_url('/thank-you-page/') );
    exit;
}
?>
```

This code snippet creates a custom WordPress template that handles form submissions. It checks if the form was submitted using the POST method, processes the form data, and then redirects the user to a thank you page using the `wp_redirect` function.