Product, base product, and variant

The base product stores the information common to all product variants, while the variant stores the information that differs between the variants of the product. The base product is connected to a tax class in order to be able to calculate the correct price with and without VAT.

Products that only have one variant - like a pair of one size, one color sunglasses - are still made up of the two levels base product and variant. The attributes for a product are defined as fields in a field template, and the field template for a product is always divided into two levels, one for the base product and the other for variant. 

The sellable item always includes the variant level. While a product can technically exist with data only on the base product level, any sellable product has to include the variant level.

The variant level stores information about price and stock balance.