Roughly (and this varies by company) they define/design the functionality of a product, subset of a product of just one feature of a product, keeping in mind th

Roughly (and this varies by company) they define/design the functionality of a product, subset of a product of just one feature of a product, keeping in mind the customer/market needs, the symbiosis with the rest of the application and the technical/engineering implications. Furthermore they drive the implementation - either make or delegate implementation schedule, development, testing, deployment, and work with marketing/sales on how to present it to the public (or how to position it within the product). I have the idea that product managers are often what I the other day heard being called 'intrapreneurs' - people with an internal motivation to create (like entrepreneurs) but who like the things that a larger organization can provide them and that they wouldn't have if they were on their own (secretaries, proper testing team, specialized roles for various tasks etc.).