Marty Cagan

It doesn't matter how good your engineering team is if they are not given something worthwhile to build.

We need teams of missionaries, not teams of mercenaries.

To be absolutely clear, the product manager is not the boss of anyone on the product team.

Just as you need to know the language of computing, you also need to know the language of business. If you have never done so, you need to take a course in the basics of business finance.

Rather than being measured on the output of their design work, the product designer is measured on the success of the product.

Modern product marketing managers represent the market to the product team—the positioning, the messaging, and a winning go‐to‐market plan. They are deeply engaged with the sales channel and know their capabilities, limitations, and current competitive issues.

These are called outcome‐based roadmaps.

Outcome‐based roadmaps are essentially equivalent to using a business objective–based system such as the OKR system. It's the format that's different more than the content.

ome companies do formal business cases, and some are informal, but either way it boils down to the need to know two things about each idea: (1) How much money or value will it make? and (2) How much money or time will it cost? This information is then used to come up with the roadmap, usually for the next quarter, but sometimes as much as a year out.

Once an idea makes it to the top of the list, the first thing that's done is for a product manager to talk to the stakeholders to flesh out the idea and to come up with a set of “requirements.”
These requirements might be user stories, or they might be more like some form of a functional specification. Their purpose is to communicate with the designers and engineers what needs to be built.
Once the requirements are gathered up, the user experience design team (assuming the company has such a team), is asked to provide the interaction design, the visual design, and, in cases of physical devices, the industrial design.