Not Invented HereNot Invented Here (or NIH) refers to the problem when people in companies continue to ignore existing solutions to problems because it was not created in-house. It is endemic to the computer industry (but by no means limited to it).
In many cases NIH occurs as a result of simple ignorance, as many companies simply never do the research to know if a solution already exists. But equally common are deliberate cases where the engineering staff rejects a solution, typically because they believe they can do better.
Many millions of manhours and billions of dollars have been wasted as a result of NIH.