The basics of php routing

Question

I'm seeking for a how-to guide or explanation of the most fundamental PHP routing.

For instance, I want to use the get function of a route class to supply the data when someone clicks on a URL like mywebsite.com/users, much like laravel does.

Route::get('users', function()
{
    return 'Users!';
});

Can somebody explain how to do this or provide me with some more information?