What are the steps to perfect a security interest under Art. 9 of the UCC? For each classification of property, what is necessary to perfect the Art. 9 security interest in this property? Specifically what is a purchase money security interest in consumer goods and why does that matter?

Article 9 of the UCC describes different types of property that may be used for collateral. What are the various categories of property under Art. 9-excluding securities since different rules apply to how security interests are created, attach and are perfected in securities.  What are these other types of property and why is that important? Note-remember that the UCC does NOT cover real estate.