Bundling is the practice of supplying two separate products together so that consumers who only want one must buy both.

A more subtle form of bundling is to give buyers who buy products together a discount.

Usually, if a supplier bundles its products, then consumers have the choice of simply going to another supplier who does not bundle. However, if a monopolist bundles, it can be a way of leveraging a monopoly in one market into another.

Examples of bundling include 3M's offers of discounts on its very strong Scotch Tape and Post-it Note products to buyers who also bought other products, and Microsoft's inclusion of its web browser and media player "free" with its Windows operating system.

Of course, less controversial examples of bundling happen all the time. The commonest familiar example is the inclusion by consumer goods and food manufacturers of a new product with an already established one, in order to encourage consumers to try the new product.