In the 80s and 90s, robotics and phyiscal computing was an expensive and difficult endeavour.
An art teacher, Massimo Banzi, wanted to make a computer that was able to be used by artists and others who just want to do things without having to study computing.
The original Arduino is a rectuangular device about 7x5cm, which has up to 22 “pins” that connect to the outside world, to control sensors, lights, motors and other things. You write programs on your computer and transfer them to the Arduino over its USB cable.
Once programmed, the Arduino retains its program and can be powered by AC plugpack, battery, or from a USB power bank.
The arduino is programmed in a simplified variant of the “C++” programming language, known as “Processing”.
There are now dozens of devices compatible with the Arduino processing environment, ranging from the size of a thumbnail up, costing from a few dollars.