You can order the electronic components online from a variety of sources. These URLs are for major suppliers who stock the components used in this book. We have also provided some links to the basic electronic guides:
Adafruit industries: http://www.adafruit.com/
Cooking Hacks: http://www.cooking-hacks.com/
Makeshed: http://www.makershed.com/
Element14: http://www.element14.com/
RS Components: http://www.rs-components.com
Wikipedia article on electronic symbols: http://en.wikipedia.org/wiki/Electronic_symbol