UI vs. API. vs. UAI
First we built a user interface (UI) when the application was just going to be operated by humans. There’s a whole branch of study around good and bad patterns in that design practice, focusing on how we make things easily operable by humans. Then we added an application programmable interface (API) when we wanted the application to be operated by other applications - integrated programs. Similarly, there are whole conferences and books about what good design looks like for these interfaces, ai