it means you make a list of 20 companies (existing, real companies) that you think would be your perfect customer. This is a very good tip as it helps you focus

it means you make a list of 20 companies (existing, real companies) that you think would be your perfect customer. This is a very good tip as it helps you focus resources. The biggest benefit is that you define the characteristics of your customer segment. In fact, it becomes very simple to find out if your product is suitable for this customer segment since you can contact any of those companies (or similar) on that list and test product fit.