Eric Ries began his career the wrong way. He and his team at a startup called IMVU spent six months building a product they were certain customers would love. When they launched, almost nobody used it. The problem was not the product. It was the process. They had treated assumptions as facts, built without testing, and emerged with something built for the customers they imagined rather than the ones who actually existed. Ries argues that a startup is not a small version of a large company. It is an organisation operating under extreme uncertainty. Its job is not to execute a known plan. Its job is to find a plan that works. The way you do that is through validated learning: running experiments to test your most important assumptions before committing resources to them. Validated learning is different from just collecting feedback. It requires forming a specific hypothesis, designing an experiment to test it, and measuring the outcome in a way that genuinely confirms or refutes the hypothesis. Opinions and gut feelings do not count. Behaviour does.