There are so many different kinds of Arduino boards out there that you’d be forgiven for getting confused. What should you buy? What is more suitable for your project? Let us help, with this beginner’s Arduino buying guide!
This guide is also available as a video:

There are literally hundreds of different types of Arduino and Arduino compatible boards, so we couldn’t cover them all. However, we can talk about the most common, most useful, and most widely supported.
Before we get started, if you only want a table of numbers, check out the Arduino list at Sparkfun. I will approach this from a different point of view: from the point of view of an Arduino beginner, looking for your first development board, or after finishing your starter kit.
The Clone Wars and Arduino vs. Arduino
A little note before we start. Prices are correct at the time of writing, and where possible links to AliExpress where you can buy Arduino compatible clones for a fraction of the cost of branded Arduino models.
It is important to understand that these are not «cheap Chinese knockoffs», at least not in any illegal sense. Most of the Arduino hardware is released under an open source license, which means anyone is free to make their own copies (and even add features missing from the original design) as long as they label it «Arduino compatible» and not «Arduino «. ‘(Which is a trademark).
If you buy an original branded Arduino, a significant portion of what you pay goes to the Arduino Foundation, which goes to fund educational programs and further develop the brand. Things got a bit more complicated with a recent trademark dispute where the «original» Arduino LLC (the one that owns arduino.cc and with which you are probably most familiar) can only use the Arduino trademark in America and was forced to rebrand as Genuino outside the USA. If you are buying a branded Arduino in Europe then chances are you are actually paying money to Arduino SRL (Arduino.org) an Italian company originally known as Smart Projects, which used to be solely in the manufacturing business.
Like I said — it’s messy — and you’ll save a lot of money if you just buy clones.
With that out of the way — please don’t start a comment war on this — let’s start.
United Nations
With clones under $3, the Uno, while not the first Arduino board, remains the most popular. It’s also the model you’ll find included with most starter kits, and for good reason. Now it’s Uno, which is the standard format for upgrade «shields», i.e. boards that offer additional functionality. you can connect on top, and can often stack with each other.
About the size of a credit card, it has 14 digital I/O pins and 5 analog pins, and runs on 5v. It can be powered by either a USB cable or up to 12V DC via a female connector.
At the heart of the Uno is an ATMEGA328P with 32 KB of program memory, which is small by today’s standards. At some point, you will probably reach this limit, but as a starting device for learning, the Uno is perfect.
Leonardo
Leonardo looks deceptively similar to Uno, even though they are completely different. While the Leonardo has the advantage of being able to emulate a USB device so you can create your own keyboard, for example, it also has a number of quirks and is not compatible with all Arduino shields.