The Products API allows a merchant to create an online store catalog, which is the list of products and offers that are available on Google Shopping. Merchants can use the Products API once they have created their merchant center account, and are ready to upload an initial set of products via the API.
The Products API uploads product information to the Shopping Merchant Center database. It also provides a number of methods that allows one to access, update or delete product information one at a time, or many at a time, in batch mode.
Although merchants have the ability to load products using a file called a Primary Feed, there are several advantages to creating, updating, and deleting products using the Content API that includes faster response time and the ability to update multiple products' data in real time, without the need to manage multiple supplemental feeds. Note that it may take up to several hours for product changes made by API calls to be seen in the Shopping Merchant Center database.
The term "product" refers to the physical unit that is to be displayed on a merchant's Product Detail Page for listing in an online location like Google Shopping.