Throughout all the projects of this book, we are going to make use of the Raspbian operating system. More specifically, we will be using the Jessie Lite version of this operating system. Raspbian is the foundation's officially supported operating system and the one for which there is most community support for. It is derived from the Debian Linux operating system; so if you have used that or any of its derivatives (like Ubuntu) before, you should feel at home with Raspbian. I have decided to go with the Jessie Lite version of Raspbian for a couple of reasons:

1. All of our projects will run headless (without a monitor, keyboard, or mouse), so why have a display manager use up our resources?
2. The lower footprint of this operating system, in terms of memory and storage usage, will give us access to more of the computer's resources to use for our projects.

So, head over to https://www.raspberrypi.org/downloads/raspbian/ and download the latest version of the Jessie Lite operating system. Once this ZIP archive is downloaded on your computer, you will need to copy it onto your micro SD card.

Until recently, there was a different way to copy an image file to an SD card in every different operating system; the open source piece of software, Etcher, sets out to solve this problem. Etcher is freely available for pretty much all operating systems, so we only need to document one process for all operating systems rather than detailing a different method for each OS. Etcher will run on any operating system that can run Electron. You can check the full list of supported operating systems for Electron on their website at http://electron.atom.io/docs/tutorial/supported-platforms/.

So, to get started with Etcher, head over to their website at https://etcher.io and download the latest version for your operating system. Run the installer as per the standard method for your operating system.

Once you have Etcher installed, open it and you should be presented with a screen like the following screenshot:

Click on the blue Select image button and browse to the Jessie Lite ZIP archive you just downloaded; there is no need to extract the ZIP archive with Etcher. You will then be presented with a screen like this:

At this point, you should insert your SD card into your computer's SD card reader. Etcher should automatically detect your SD card and progress onto the third section of the process. Click on the blue Flash! button to begin the copying process, and Etcher should display something similar to this:

You will be shown a completion estimate, the percentage copied, and the transfer rate in the Etcher window. Allow Etcher to complete this; then exit the program; and remove your SD card from your computer (no need to safely remove or eject it, Etcher has done it for you!).

You have now copied Raspbian Jessie Lite to your SD card, and you're ready to move on to our next section, Connecting to the GPIO headers.