Product definition is the process by which a team describes what it is that they are building for their target customer(s).
There are many levels to product definition - a one-page summary or landing page is appropriate at the very beginning of the product development journey; as the team builds knowledge about the market, the customers and their needs and wants, more detail will come in making the product definition actionable by technical developers.
This article builds on content developed by the Martin Trust Center for MIT Entrepreneurship for MIT's Orbit Knowledgebase and is licensed under CC BY-NC-SA 4.0.