If you've heard about pull-up resistors, and not too sure about the theory and operation of them with your Arduino then a new tutorial published by James Lewis will be of interest. He runs through the pitfalls of not using them with digital inputs, and how to use the internal pull-up resistor in the Arduino's micrcontroller as well as using external resistors to stop floating digital inputs. Furthermore he demonstrates this in several videos, for example:
Some very useful notes for the beginner and possibly for the more experience user as well, so visit James' website to get started. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you've been looking for an approachable, easy to read book to learn about Arduino, or as a gift for someone else - you can't go past "Arduino Workshop - A Hands-On Introduction with 65 Projects” by John Boxall. Arduino Workshop takes the reader from having zero knowledge about the Arduino platform, electronics and programming and leaves them with the know-how and instructions on everything from blinking an LED, to robotics, wireless data, cellular communications, Internet connected systems and more. For more information including a sample chapter and table of contents, visit the book page.