Arduino itself is an Italian company that focuses on open-source things, such as Hardware and Software. The hardware that Arduino makes are electronics that are usually Arduino small "computers" that make single-board micro-controllers.
These electronics, usually can be programmed and be used to make things out of it. From a simple light that blinks, to making robots using Arduino.
Some of the known Arduino boards are:
Arduino UNO
Arduino Nano
Arduino Mega
Arduino Due
and many more.Â
The program that is mostly used to program Arduino boards, is called Arduino IDE.