What does $this refer to in magento's actions?

I'm looking at this file:

https://github.com/magentomirror/magento-mirror/blob/开发者_运维技巧magento-1.5/app/code/core/Mage/Catalog/controllers/ProductController.php

what does:

$this

and

$this->

refer to?

It refers to the object "Mage_Catalog_ProductController" in that case. "$this" refers to the current object, so it's relative to which class it's called from.

PHP Manual for OOP