What makes an arduino board so special?

I've seen arduino boards (or something comparable) in most DIY circuits, but I wonder why everyone uses them. What makes them so necessary and/or useful for building circuits?

Bot13985 years ago
The Arduino board is incredibly versatile,cheap, and accessible to all hobbyists.Its is a open source prototyping platform which uses the AVR series of microcontrollers.Circuits can easily be prototyped using the arduino and it gets programmed in the C++ language which is based around C.The arduino can perform even the most complex functions.For more detailed information take a look here.