I have been asked a few times to explain what I was doing - technically speaking.

An Arduino is a microcontroller, that is a tiny computer that you can find in a lot of appliances. Lets say a coffee machine that has a green light when the temperature is ready (there is a temperature sensor that is read by the microcontroller and depending on that reading turns the green led on or not), or a bread maker that has a preset for making pizza dough or whole wheat bread.

Now, those are probably closed source, made by some people who studied years to learn how to program those and spend lots of time working on a cheaper chips (a few ¢) and unfriendly to make the appliance price lower. 

Arduino is different, because it is an open source microcontroller, that is made to be more friendly user, and that has a big and growing community of makers using it. It cost between 2$ and 30$ depending of where it is made and the board’s capacity. Because it is open source some businesses made compatible boards, like Teensy that has the ability to be compiled as a midi instrument and Flora that is sewable to make wearables, just to name a couple.  There is too a large quantity of easy to use add-ons (motor shields, audio adapters, GPS…) So now, as long as you can access Internet for resources, and have a few dollars, you can make your own Something That do This (optionally when That Happens). How cool!

So that is what I use when I want sensors for my music, if I want to move motors, name it. It is still far from being plug and play, you have to code, do electronics, but, it is now a lot more reachable than it was, lets say, 10 years ago.

I made a How To Control Stepper Motors with MIDI using Adafruit Motor Shield V2 on and Arduino Leonardo with Teensyduino and TeeOnArdu.