Windows are a critical element of architectural design. Window selection not only significantly impacts the aesthetics of the project, but also affects the energy efficiency, comfort, durability and sustainability of the building once construction is complete. This learning unit will address some of the more popular window choices available today and provide a comparative review of the features and benefits of these very important building elements. This learning unit will also introduce learners to the standards, tests, and other performance metrics that will enable specifiers to select the right window for the right application.