When you load a View from the Controller, there could be a situation when you don't actually know which view to load - the name could be dynamic. For example, you would use different Blade templates for sending emails. There is a neat function to assure your chosen View file actually exists.
It goes as simple as this:
if (view()->exists('emails.' . $template))
// ... sending an email to the customer
I personally would consider this approach a bad practice - you should catch that error in Controller or elsewhere in the logic before actually calling the View. But if for some reason you get to this point - function exists() can be handy.
More info about Views - in the official documentation.