Is there is a way to get query string back in PHP?

I have:
`http://mywebsite.com/cars/BMW/` `http://mywebsite.com/List.php?categories=/cars/BMW/`

```
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/]*)/$ /List.php?categories=$1 [L]

```

I want to capture categories value in PHP .Please note the parameter format '/cars/BMW/'