so my starter kit talks about the arduino IDE using "processing" language, while many other locations reference "C"
just curious which is it, or is it both somehow (like processing is a subset of C)?
Processing is Java based, and Arduino is C/C++, as it uses a C/C++ compiler, and Processing uses Java, so although they may have functions with the same name, and the same setup/loop layout in the IDE they have nothing in commom
why does the book (written by one of the Ardunio guys Massimo Banzi) say arduino is Processing based, if its based in C?
Check carefully - the Arduino IDE is Processing based (as in, it's based on the Processing IDE's source code), and the Arduino-provided libraries/development environment are written with Processing concepts in mind.
Beyond that, though, the Arduino ecosystem is just a library on top of the avr-gcc compiler - I, along with many others, just treat it as C/C++ with a new API.
gotcha, that makes more sense. Thanks.