Hi, I personally have not applied any major Design Patterns to any of the projects that I've done, but nevertheless, I know some of the problems that I've solved actually could have been more elegant if I knew the Design Pattern behind it One of IBM's objective is "Given its definition, apply a pattern". For those who has knowledge of the real exam, heh, can you pls share the Design Patterns it ask for? Or, how about just elaborate what kinda Patterns should I concentrate in. There're way too many Patterns out there. Any hint would help, thanks.