Ensembles are a way to group products that are sold both as individual items, and as parts of a collection. A good example of this would be items in a gift basket. Let's say that you sell a gift basket that includes a number of bath items: one or two soaps, a shampoo and conditioner, and a lotion.
The items in this basket are also sold separately and are available as separate items in your catalog. This raises the question: how will these items be listed in your catalog feed? The items in the basket each have their own product IDs, and the basket itself has its own product ID, separate from the items inside it. But a person purchasing this basket has demonstrated at least a partial affinity for each item in it, and we need to take that affinity into consideration when deciding on recommendations.
The way that we note this is by indicating that each of these items is also a child of the gift basket in which they are also sold together, and we do this by using the product parent ID in the Product Feed File.
For example, let's say that this gift basket has an ID of "00010." The shampoo in it has an ID of "001." The line that describes the shampoo in the Product Feed File would look like this:
product_id|name|price|recommendable|image_url|link_url|product_parent_id 001|Scented Shampoo|12.99|true|assets/images/shampoo-001.jpg|products/shampoo-001.html|00010
Now the gift basket and the shampoo are linked. With this link in place, all purchases of the gift basket will have a link to each item in it, and can share affinity data with them. However, not all purchases of the shampoo will share affinity with the basket, as separate purchases should only reflect on the shampoo itself.