What does ::class mean in laravel 5.1 [duplicate]

This question already has an answer here:

• What does ClassName::class mean in PHP? 1 answer

When I add custom service providers in app.php, I used to insert as follows

'Something\Somewhere\SomeProvider',

But in Laravel 5.1, It changes as follows

'Something\Somewhere\SomeProvider::class',

What does it mean ?? I like to know about ::class usage in php.

via Chebli Mohamed