Customer development (abbreviated as custdev) is testing an idea or prototype of a future product on potential consumers. The term was coined in the 1990s by American serial entrepreneur Steve Blank. In his book Four Steps to Insight: Strategies for Building Successful Startups, he formulated customer development, a customer-centric approach to building a business. According to this concept, the product must necessarily solve the client's problem. First, the problem is identified, then the product is developed, and not vice versa.