Validation terms, defined

Plain definitions of the terms founders hit while validating an idea — fake door tests, problem validation, customer discovery, and how market and product validation differ.

• Customer Discovery
  Customer discovery tests your assumptions about who your customer is by talking to them before you build. The questions that work, and the ones that lie to you.
• Fake Door Test
  A fake door test measures demand by advertising a product before it exists and counting who tries to get it. How it works, and where it goes wrong.
• Market Validation vs Product Validation
  Market validation asks whether enough people want this solved. Product validation asks whether your build is the thing they want. Why mixing them up is costly.
• Problem Validation
  Problem validation confirms the problem you want to solve is real, frequent, and painful enough that people already try to fix it themselves. How to do it.