Laravel Collective Syntax

I'm learning laravel (5.5) from a book. I installed laravel collective, the book says, to link a css file write like this: It works fine. but in the output two empty {} braces appear (because they are not being used as part of the syntax). So, I removed them and it still works fine. Question is which syntax is correct? this or {!! HTML::style('css/app.css') !!} ???

via Chebli Mohamed