Product developers ask themselves excellent questions about their users: Do people need my product? Can people use my product? Why do people sign-up, then not use my product? However, product developers answer their excellent questions in invalid and unreliable ways. It is shocking to see how much effort product developers put in writing elegantly structured, refactored code, with good unit test coverage in an agile environment, and yet, their products fail miserably. This talk inspires designers, product managers, and developers to implement valid and reliable ways to answer their most burning questions. It helps them validate or invalidate their assumptions on their own – cheaply, and quickly, by using simple user research techniques with a main goal in mind: developing products people need, want, and enjoy.