Additional reference material, sources and citations:
Arduino official website:
This is the official website of the Arduino platform, and contains links to purchase Arduino boards, reference information and diagrams, and FAQs regarding the platform. Here is also where you can download the Arduino IDE, to write and upload your own programs.
The Make official website:
This is an excellent source of hobbyist information for the Arduino platform, and in addition to containing detailed, easy-to-follow project descriptions, has a store where they sell starter kits containing Arduino boards and additional hardware used in beginner-type projects
C programming dot com:
A great place to begin learning the basics of programming in C.
This is an excellent website for purchasing bulk components, as well as inexpensive tools and all sorts of knicknacks, doodads and widgets.