Most people validate the wrong thing at the wrong moment. They ask friends whether the idea sounds good, hear yes, and treat that as evidence. Then they spend six months building and find out that liking an idea and paying for it are unrelated.
Validation is not one step. It is a different question at each stage, and asking them out of order wastes the most expensive resource you have.
Before building, the question is whether the problem exists and whether anyone is already paying to solve it badly. Before charging, the question is willingness to pay, which is not the same as stated interest. During the MVP, the question is real usage, not signups. Before scaling, the question is acquisition and unit economics, because a business that only works when you personally sell it is a job.
This cluster covers each of those in turn: what to test, how to test it cheaply, and what result should make you stop.
We also run our own experiments here. Small ones, under a thousand dollars, with the actual numbers published: what we spent, what came back, and what it told us. Each one ends the same way, with a decision rather than a reflection. Build, change or kill.
The point of validation is not to prove yourself right. It is to find out you are wrong while it is still cheap.
In this cluster
Where it goes next: once an idea survives validation, it has to become something people can buy. That is Shipping.