Triple sec is a clear orange flavored liqueur used in drink making as well as a flavoring for various desserts. It is one of the main ingredients in a margarita, a cosmopolitan a Long Island iced tea, and a whiskey sour. Other orange liqueurs include Grand Marnier, Cointreau, and Curacao. The main differences between all of these is typically price and quality.
If you don't have triple sec you can use one of these alternations. We've included options that include no alcohol: