:: vs ->

I should probably know this but it's hard to google for

what's the difference when using classes in php between saying object::method() and object->method()

also, while i'm on the subject, what's the significance of beginning a method with "__" as in $object->__get() - i guess this is a naming convention, but i can never get why you would use __get() over just get(); i'm just not sure what that implies

thanks