API as a term is context-dependent. It is one of those terms where it is easy to cause disagreement—as is evident in this thread—because you failed to define wh

API as a term is context-dependent. It is one of those terms where it is easy to cause disagreement—as is evident in this thread—because you failed to define what you really mean by your use of the term. API is a term of art—it means different things to different practitioners. What the term means to you will depend on where you work on the stack. For a web-based application served over the Internet: - an end user will need to work visual APIs (web GUIs) rendered using HTML/CSS/JS; - a frontend engineer will need to work with text-based APIs (web services) exposed by web servers on the Internet; - a backend engineer will need to work with system APIs exposed by web & DB servers over the internal network; - a DBMS engineer will need to work with low-level APIs exposed by the OS to internal processes. At the top of the stack the final user is an end user while at the 2nd-4th levels, the final user is a programmer. The same term is used at different levels of the stack but the context makes it absolutely clear who the final consumer of each API really is.