Google redefines the “product_type” attribute, taking product categorization to a new level.
As the word “product” covers such a vast range, it was always difficult to know exactly how to categorize your items. 

Below are some screenshots to help you along in understanding the newly updated attribute and the process of including this within your feed.

Although it may sound like a mammoth task with endless possibilities to categorizing your product, unlike other attributes, Google have made it a lot easier to find your exact match. Google offer a “Browse The Taxonomy” found here! which allows you to navigate through the categories and even provides you with a copy of the text and .xml for input into your feed.  (fig 1.)

This addition allows you to individually stipulate each of your items into relevant “families”. The “Parent” of the family would be the category in which it falls, such as a PlayStation 3 would be filed within the Electronics family. You can then chose subcategories or “children”. 

Children in the case of a PlayStation 3 would be, Video Game Consoles > Home Game Consoles > PlayStation 3. Giving the final result as

“Electronics > Video Game Consoles > Home Game Consoles > PlayStation 3″ (fig 2.)

However, If you are selling PlayStation Games, It would not be a simple addition of “> PlayStation 3 Games” as these themselves are not categorised within “Electronics”. The Parent Category for PlayStation Games would be Software with the Children being Video Game Software > All PlayStation Games > PlayStation 3 Games. Giving the end result as

“Software > Video Game Software > All PlayStation Games > PlayStation 3 Games” .

As you can see Google do note potential errors and correct these for you by a simple click on the blue arrow (fig 3.)

The reason I used the above example is I believe many user would be under the impression that it only right to include the PlayStation games alongside the PlayStation itself. However in the following example you can clearly see a “Family Tree” in which that impression would fall.

Take for example “Football Apparel”. If you followed the previous example, you may believe this would be categorised in Clothing, contained within the Clothing & Accessories Parent Group where as a Football itself would fall under the “Sporting Goods” Parent. Were you thinking that? Was it only me? Well, if you were, think again. This is one example in which all Football and Football related products are contained within one parent category. The parent category being “Sporting Goods” with the child being Football. From there, the tree branches out into multiple sections. Although the available options vary greatly, the subject matter remains the same throughout. Apparel, Accessories, Protective Gear, Trading Cards etc. all of which could easily be placed within other corresponding categories (e.g Collectibles for the Trading Cards). (fig 4.)

As with so many attributes Google does allow you to use previously created categorization for your items but urges you to, if possible, to use the standard taxonomy supplied. If you do chose to use your own set categories, Google prefer you to implement breadcrumbs. (e.g Media>Music>Classical) rather than say Classical alone.

It is always best to take extra time when deciding on the correct category. If you believe your product fits well within two or more categories you can include these by simple placing each category in quotation marks followed by a comma before entering your second category (again contained within quotation marks).

Hope this helps, best of luck!