A product line is rarely designed all at once. It accumulates — one item added to catch a missed segment, another to match a competitor, a third kept alive out of habit long after the reason for launching it has faded.

This book treats product policy as a deliberate discipline: how many lines to offer, how much variety to build within each one and what that variety actually costs in margin, brand clarity, and collaborator support, how to design an individual product item, what makes a new product adoptable, and how to manage a product’s trajectory across its life cycle.

Written for the person who has to decide what belongs in the line and what does not.