Textbook publishers use a packaging strategy known as often the publisher will combine highly complementary products such as a new textbook and access code for online software that students can use to test themselves on new concepts and principles.

Textbook publishers use a packaging strategy known as Bundling

Explanation:

What Is Bundling?

Bundling occurs when companies package all their product as one combined unit. This lowers the price for which it was going to cost if sold as just one product not combined. It is a great marketing strategy in which companies can benefit from selling their different products as a package. There is a relation amongst the combined products but they can also consist different items which are applicable to the same customer.

Companies are able to sell bundled products at lower prices which may increase the demand of those products.