Glossary

A claim about the world that the plan depends on, but that has not yet been tested. Most startup failures trace back to one untested assumption.

A product that builds an interface, workflow, or service around one or more third-party AI models. The label describes an architecture; it does not decide whether the product is useful or defensible.

The ongoing process of finding and talking to the people who have the problem you want to solve, before and after you build. Discovery is where most of the actual learning happens.

The single assumption that, if false, would invalidate the rest of the plan. Finding and testing this assumption is the highest-leverage work in early-stage validation.

The rate at which existing customers stop paying. A SaaS business works when new customers per month exceed churned customers per month, and the gap is growing.

The conditions that make a product harder to copy or replace after competitors gain access to similar models — such as distribution, workflow integration, permissioned data, trust, or switching costs.

The first person who pays for the product, not the first person who says they would. The first customer is the unit of evidence that matters in pre-revenue work.

The overlap between your background, skills, audience, and domain experience, and what this specific idea needs. Some ideas need a domain expert. Some need an audience. Few need neither.

A bounded period during which a customer can use the product without paying. A free trial is a real validation tool, but it tests curiosity, not willingness to pay, and complicates churn math.

The narrow description of the buyer most likely to buy, retain, and refer. Not a segment — a specific kind of customer with a specific budget and a specific workflow.

A small experiment in which you publish a single page describing the product, drive a small amount of traffic, and measure how many visitors take the next step (sign up, request access, leave an email). Cheap signal, not proof.

The smallest version of the product that lets you test the most important assumption. The MVP is a learning tool, not a finished product.

A small, often solo-built SaaS that targets a narrow use case, serves a small audience, and is typically priced below $50/month. Validation challenges are the same as larger SaaS; the cost of being wrong is smaller in dollars but larger in proportion.

A durable advantage that protects customer relationships or margins and can strengthen over time. For an early startup, a moat is a hypothesis to test, not a claim to announce.

Exposure to upstream changes in model behavior, price, limits, availability, or terms that can alter the product without the founder changing its own code.

The point at which the product satisfies a real, repeated demand from a specific audience. It is observed, not declared — you know you have it when retention and word-of-mouth improve without paid acquisition.

A conversation with a potential customer about their life and workarounds, not about your product. The interview is your chance to learn what they actually do, not what they say they would do.

The discipline of testing the assumptions behind your idea — the problem, the customer, the willingness to pay, and your ability to execute — before you commit months of work to building it.

Software sold as a recurring subscription rather than a one-time purchase. The customer relationship is continuous, so the product has to justify itself every month.

Run cheap experiments that test the problem, customer, and willingness to pay before committing to a build. Validation produces evidence, not certainty.

Whether a real person will trade real money for the solution, in a real transaction. Only money tests money — interviews and surveys do not.