A concept is basically an A3 sheet of paper (12" x 16") with predefined sections for questions that should be answered before you enter into a conversation with the development team.
Think of a concept as a flexible minimum specification, on one page as shown in the preceding figure. The three questions to consider are as follows:
What is the product’s impact? (What gets better in the customer’s world when he or she uses the product?)
What are the product tradeoffs you’re willing to make and what must you stand your ground on?
How can you, as a stakeholder, arrive prepared for a conversation with the development team?