The Raspberry Pi only boots from an SD card (or micro SD card for the B+ and v2 models), and cannot boot from an external drive or USB stick (well that's not strictly true, but is beyond the scope of this book).
It's recommended that you use a Class 10 SD card for performance, but a Class 4 or 6 card will be fine for this project. You'll need to have a minimum card size of 4Gb.
Now that we have our Raspberry Pi board and SD card to hand, we need to prepare the SD Card specifically for our home security system. We're going to use the standard Raspbian operating system as there really is no reason to use any other distribution; it's the de facto choice for the Raspberry Pi.
You'll need to grab the ...