Although there are no hard and fast rules about the smart casual dress code, typically it means men should wear a pair of casual trousers and a tailored shirt and jacket. However, there are cultural differences with this dress code.
According to the New York Times, the term "smart casual" was adopted in the early 1990s as a reprieve from the Silicon Valley-style power suits worn in the 1980s. This dress code is open to cultural interpretation, so it may mean one thing in the United States and something completely different in Europe. However, most clothing designers agree that smart casual is a step up from the traditional "casual Friday" look seen in some offices.