The "Not Invented Here" (NIH) problem refers to the cognitive bias where individuals and organizations reject or undervalue external ideas and innovations in favor of internally developed solutions. This can lead to a lack of innovation, wasted resources, and missed growth opportunities. The NIH problem is often driven by pride, ownership, and fear of loss of control, as well as confirmation bias, groupthink, and the desire to maintain control over one's own work. To avoid this problem, it is essential to be open-minded, collaborate with others, and leverage existing solutions, such as open-source software. By following five rules - being smart by accepting you're not the smartest, not making it your baby, working in a startup environment, fostering an organization that embraces change, and encouraging developers to work on open-source projects - individuals and organizations can overcome the NIH challenge and foster innovation.