In economics, marginal cost is the cost of producing one incremental unit at a given level of production. So if you are currently producing 1,000 bobbleheads a year, what is the additional cost of producing the 1,001th? If it will result in more marginal revenue than marginal cost, you should generally do so. In the book I show that in the old IT world, many decisions made by considering total cost should now in the digital world be made by comparing marginal costs to marginal returns. The tools of the digital world allow us to make decisions at the margins, and doing so adds economic value.
— War and Peace and IT: Glossary, Mark Schwartz