very general low-level business services used in many business dom ains Business infrastructure CurrencyConverter (AKA LOW-level Business Services) (relatively) high-level technical services Technical Services and frameworks (AKA Technical Infrastructure Persistence Securty High-level Technical Services) low-level technical services, utilities and frameworks Foundation data structures. threads, math (AKA Core Services, Base Services fe,DB. and network∥o LOW-level Technical Services/Infrastructure width implies range of applicability y