This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
byte, short, int, and long are all "integral types", meaning they can only represent integers -- numbers with no fractional parts. None of those types can hold 3.14, but they can hold 3. float and double are "floating point types", and they can represent numbers with fractional parts.