The product identifier (item_group_id) is a unique identifier assigned to the main, base product. For example, if we have a "Classic T-shirt", it will have one main product identifier (item_group_id).

The main product "Classic T-shirt" - will have a product identifier item_group_id, let's assume it will be "1". Product variants - will have their own separate variant identifiers id, let's assume they will be marked with lowercase letters of the alphabet "a", "b", "c", "d". If we have many variants of the same product, their designation will look like this:

One Classic T-shirt product with identifier item_group_id: 1 can have many variants with identifier id: a, b, c, d. Variant identifiers are always associated with the product identifier.

Having product variants in the product file is especially valuable when analyzing product sales, where thanks to variants we can precisely monitor the results of individual product versions. This allows for a deeper understanding of customer preferences and the identification of the most popular combinations of features, such as size, color or style of a given product.