"But most of all, it's cool because the entire reference design
for the hardware is available under a Creative Commons licence, so
you're free to build your own if you want to. However, that's
probably a little extreme for most people, which is why you can
also buy pre-built Arduino boards that are ready for action and
available at very low prices.
"In this tutorial, the first part of a mini-series, you'll learn
all you need to get started with Arduino hardware hacking...
"The Arduino programming IDE is available under the GPL for Mac
OS X, Windows and, of course, Linux, so the only things standing
between you and your own pet hardware project are an Arduino board,
a cool idea, and of course a Box O' Tricks - some neat little parts
you can plug into the Arduino to make it do more interesting
"Arduino boards come in several varieties, but the main three
are the Arduino NG ('next generation'), the Arduino Diecimila and
the Arduino Duemilanove. These aren't competing boards - the NG
came first, was replaced by the Diecimila, which in turn was
replaced by the Duemilanove. We have an NG because we bought it a
while ago, but if you try to buy one now you'll probably only find
the Diecimila or the Duemilanove for sale."