Arduino has vibrant ecosystem of code libraries, hardware and community. It's the most popular microcontroller system for hobby and hackers with open source hardware and software there is an example of almost anything done on Arduino.
Genuine Arduino boards are manufactured to high quality by the Arduino company originating in Italy. Thanks to their open source philosophy for hardware as well as software the board designs are copied, tweaked and innovated on by many other companies who make compatible boards and shields.
All Arduino compatible boards can be programmed using the free Arduino software with sample code and other projects on the Internet guiding you.