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Let's consider the following code: class a { public $var1; function disp(){ echo $this->var1; } } $obj1 = new a; echo ' After instantiation into $obj1: '; xdebug_debug_zval('obj1'); $obj1->var1 = "Hello "; echo ' After assigning "Hello" to $obj->var1: '; $obj1->disp(); echo " "; xdebug_debug_zval('obj1'); The output: After instantiation into $obj1: obj1: (refcount=1, is_ref=0)=class a { public $var1 = (refcount=2, is_ref=0)=NULL } After assigning "Hello" to $obj->var1: Hello obj1: (refcount=1, is_ref=0)=class a { public $var1 = (refcount=1, is_ref=0)='Hello ' } One by one: After instantiation into $obj1: obj1: (refcount=1, is_ref=0)=class a { public $var1 = (refcount=2, is_ref=0)=NULL } Why does $obj1->var1 have refcount=2 when there is only one object of class a? Is it because of how the new operator makes assignment? PHP does assignment with references. When instantiated with new , no symbol/variable name is associated with that instance. But, the class properties do have names. Is the recount=2 because of this? If that is the case then a C.O.W (copy on write) has occurred with a shallow copy WRT the class instance. While the properties are still pointing to the zval's of properties created during the instantiation using new . Now, After assigning "Hello" to $obj->var1: Hello obj1: (refcount=1, is_ref=0)=class a { public $var1 = (refcount=1, is_ref=0)='Hello ' } So, when I assign a value to the property $obj1->var1 a new zval container for that property and hence the refcount=1</co

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