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.
A design pattern is a technique that comes up repeatedly in software. It's a reusable solution to the same problem. For example, it is common to want just one instance of a class in your application. Maybe it has a counter in it so you want everybody to go through that class. The solution is the Singleton pattern.
Head First Design Patterns is a good first book on the topic. The table of contents is online so you can see what you will learn.