'The MOM test' Book summary in English | As an entrepreneur, what should you ask your customers?

The book is about how to talk to your customers effectively and how not to screw up. It is based on the author's experiences and advice from other founders. The advice is based on a casual approach to conversation.
People shouldn't ask their mom if their business idea is a good one because she will lie to them. Instead, you should ask good questions to figure out whether your business idea is good. The Mom Test is a set of simple rules for crafting good questions that even your mom can't lie to you about.
The measure of usefulness of an early customer conversation is whether it yields concrete facts about customers' lives and world views. These facts, in turn, allow businesses to improve their operations.
Do not ask customers if your idea is good, or if they would buy it. Customers are only able to give you their opinions on things after they have tried it themselves or if they have researched it thoroughly. Do not ask customers what their dream product would do. Instead, ask them why they want the product or what the implications of it would be. This helps you to understand their motivations and constraints.
An opinion is worthless. Anything involving the future is an over-optimistic lie. Questions like "would you buy a product which did x?" or "what would your dream product do?" are useless because they ask for opinions and hypotheticals from overly optimistic people.
The author suggests asking the customer how they have been dealing with the problem, what other methods they have tried, and how much it would cost and be a pain to switch to a new solution. The author also suggests pricing the product in terms of the value it provides to the customer, rather than the cost to the company.
It’s important to ask where the money for the purchase will come from and who else within the customer's company will be involved in making the purchase. Finally, the author recommends asking other questions that will help the customer understand the purchasing process and potential roadblocks to the purchase.
Bad data is not useful or accurate, and can lead to bad conversations and wrong decisions. When talking to customers, be sure to gather data rather than giving compliments. Compliments are often false, and can lead to further confusion and misunderstandings. In a good conversation, be sure to focus on pertinent information and ask relevant questions.
Remember though, you don’t need to end up with what you wanted to hear in order to have a good conversation. You just need to get to the truth.
Fluff comes in 3 cuddly shapes: Generic claims (“I usually”, "I always", "I never"). Future-tense promises (“I would”, "I will"). Hypothetical maybes ("I might", "I could"). When someone starts talking about what they “always” or “usually” or “never” or “would” do, they are giving you generic and hypothetical fluff. Follow The Mom Test and bring them back to specifics in the past. Ask when it last happened, for them to talk you through it, how they solved it, and what else they tried.
Dig beneath ideas
An entrepreneur is always drowning in ideas, but they have too few ideas, not too many. Still, people adore giving us more. At some point during a good conversation, the person you're talking to may "flip" to your side of the table, which is good news. They are excited and see the potential, so they'll start listing tons of ideas, possibilities and feature requests. When you hear a request, it's your job to understand the motivations which led to it. You do that by digging around the question to find the root cause. Why do they bother doing it this way? Why do they want the feature? How are they currently coping without the feature? Dig.