How does the product vendor filtering work?

Shopify allows to assign a product vendor to each product. This can be done in the Shopify product editing page:

You can limit the random recommendations displayed to products from the same vendor of the current product. Just go to the Recommendation Tuning section from the preferences page and click on the Configure random recommendations button:

Select the Filter by product vendor option (random recommendations must be enabled as shown in the previous screenshot):

Let's say, for example, that you're seeing a product page whose vendor is Nike. The random recommendations displayed will only be products from Nike.

Please note that, if there are not enough products matching the selected criteria, the recommendations will be automatically completed using random recommendations.