Arduino is, as I’ve written about before, a great hardware platform for anyone interested in building almost any sort of homebrew electronics project. One of the best things about it is that it’s undergoing constant innovation. There are dozens of different Arduino boards on the market, so you can find the perfect hardware for any kind of project you’re working on.
Unfortunately, that same huge selection of Arduino boards can make it hard for a beginner to get started with the platform. On the official site alone, there are almost 20 current- or last-gen Arduino boards listed, and there are dozens more unofficial boards for sale on other sites. Picking the one that's exactly what you need is daunting—especially if you're not familiar with the vocab used to describe the various microcontrollers and boards.
To help make the process a little easier, I'm going to look at the most common Arduino boards on the market right now, and I'll explain how to distinguish between them.
There are three broad ways to differentiate the various Arduino boards. The first is to look at the board’s processing capabilities—the microcontroller’s memory, clockspeed, and bandwidth. The processing hardware is generally entirely determined by which microcontroller chip the board uses, and constrains what kinds of software can run on that board.
The second way to differentiate between the boards is their feature set. This includes all the stuff on the board other than the microcontroller, such as input and output pins, built-in hardware like buttons and LEDs, and the interfaces available on the board (USB, Ethernet, etc).
Finally, because Arduino is meant to be built into physical projects, form factor is very important. Arduino comes a variety of shapes and sizes.
With all that out of the way, let’s look at the boards you're most likely to want to use in your project (as of June 2013). I’ll break down the distinguishing characteristics and features of each model, as well as what kind of project that board is best for.