The term product definition represents the specification of the product and can be started way before all details of the product is known.

The product definition can contain information on different levels including:- 

• Product vision representing overall and long term product objective
• Overview of main features in scope
• Overview of main features not in scope
• Specific details required for development

A product definition can have many different formats including a combination of text documents, backlog/requirements list, pictures, diagrams, design documents,  prototypes etc

Making sure the team and stakeholders are aligned about the product to be made is a key task throughout the project. In the preface to his book “Inspired – How to create products customers love” Marty Cagan writes: It doesn’t matter how good your engineering team is if they are not given something worthwhile to build (ref 1). 

Definition of the product is usually one of the key tasks in a project It typically takes 15% of the total project time to define the product including requirements (ref 2)

Quality in product definition pays of:  

• It can cost as much as 10-20 times more to change a requirement once it has been developed (ref 2)
• Product definition and requirements defects is often accountable for more than 50% of project rework (ref 2)

Ref 1: Cagan, 2008, Inspired, How to create products customers love, SVPG Press

Ref 2: Wiegers and Beatty, 2013, Software Requirements – Third Edition, Microsoft Press