Glossary

Every concept in this sheet, plus the smaller terms it uses. Select a concept to open its card.

App store research: Studying the top apps for your problem in the App Store and Google Play: their rankings, prices, paywalls, update history and especially their recent one- and two-star reviews.

Competitors as evidence: Existing products for the same problem show that people spend money on it.

Demand signals: Public evidence that people want a solution: repeated complaints in forums, one-star reviews of existing tools, questions asked again and again, job posts for manual work, and people paying for clumsy alternatives.

Painful, frequent problem: A problem that hurts enough, and happens often enough, that people already try to fix it with workarounds, spreadsheets, hired help or other products.
Pre-sale: Taking payment, or a firm commitment, before the product is finished, usually at a discount, with a clear delivery date and a refund promise.
Problem interview: A short conversation, often 15 to 30 minutes, with someone in your target group to learn how they experience the problem, what they have tried and what it costs them.
Problem statement: One or two sentences naming the customer, the problem, how they handle it today and what it costs them.

Scratch your own itch: Building a product for a problem you have yourself, so you understand it deeply and can judge the product as its first user.
Search demand: How many people search for your problem, and whether that interest is growing, seasonal or fading, as shown by Google Trends, keyword tools and autocomplete.
Smoke test: A simple page that describes the product as if it exists and asks visitors to act, such as joining a waitlist or pre-ordering, to measure interest before building.
Success threshold: The result you decide in advance that counts as a pass, such as "5 pre-sales from 200 visitors in two weeks", along with what you will do if you miss it.

Target customer: The specific group you build for, described precisely enough to find them: role, situation and where they spend time online, such as "solo physiotherapists who book patients by WhatsApp".
The Mom Test: A set of rules from Rob Fitzpatrick's book: talk about the other person's life and past behaviour, ask for specifics, and avoid pitching your idea or asking whether they would use it.

Waitlist: A list of people who left their email to hear when the product launches.

Your advantage: What you know, whom you can reach or what you can build that most people trying the same idea cannot: domain experience, access to a community or a rare skill.