passing-by-value

In PHP, when foo = new Foo(), technically speaking, is foo an object, or is foo a reference?

Update: in http://php.net/manual/en/language.oop5.references.php it says: One of the key-points of PHP5 OOP that is often mentioned is that "objects are passed by references by default". This is not completely true. Why is that? The following is a reason which I don't know is completely true or not: I think loosely ...