Is a practice used by businesses in which they encourage a customer to buy related or complementary products of an already purchased one.

The purpose of cross-selling can be to increase income or to protect the relationship with the client.

When using cross-selling it is important to ensure that the added product or service sold enhances the value the client gets from the business that is selling the product.

It is considered to be illegal if there is a tie-in between the original product and the complementary one if the customer must get the first to be able to buy the second.