Which to use Auth::check() or Auth::user() - Laravel 5.1?

No, the accepted answer is not correct.

Auth::check() defers to Auth::user(). It's been that way since as long as I can remember.

In other words, Auth::check() calls Auth::user(), gets the result from it, and then checks to see if the user exists. The main difference is that it checks if the user is null for you so that you get a boolean value.

This is the check function:

public function check()
{
    return ! is_null($this->user());
}

As you can see, it calls the user() method, checks if it's null, and then returns a boolean value.

If you just want to check if the user is logged in, Auth::check() is more correct.

Auth::user() will make a database call (and be slightly heavier) than Auth::check(), which should simply check the session.

I recomend you to define $user = auth()->user(); If you want to check if user is authenticated or not and user model properties like email, name, ... in your code.

Because auth()->user() and auth()->check() both will query to database. If you want more speed in your apps, define $user = auth()->user(); then you can us it in your codes and also you can check if user is authenticated via $user == null;.

Don't use auth()->check() and auth()->user() both in one function or one block of code to have low queries to database and more speed apps! ; )