So you finally decided to hop on the Arduino bandwagon and start making electronic projects as a fun hobby. As a beginner ...
ARDUINO_LIBS += my_custom_library in your project Makefile and produce a directory ... not just the ATMEGA328P on the Uno. In short, this feature is an exposition of the features of AVRDUDE ...
There are also plenty of tutorials circulating online to help you learn and troubleshoot projects ... official tutorial on Arduino's website. The options are far from short, with thousands ...
In short, Arduino LLC has been working on developing the Arduino platform, software, and community while Smart Projects / Arduino SRL was the major official producer of the hardware for most boards.