terconnection, etc.), and management-related terms (QoS resource management, class of service, fault, etc.). So, QoS terms have been clas- sified into general terms and three broad areas which include service, network, and management. 1.7 Discussion This introductory chapter has provided information regarding the convergence of the telecom and Internet worlds which is being realized in the first two decades of the twenty-first century and it is expected to continue toward a full, all-IP world. However, the traditional telecom world is based on strict end-to-end QoS provisioning, such as QoS in telephone networks for voice services (including fixed PSTN as well as PLMN such as the Global System for Mobile communication (GSM)), TV broadcast networks for TV, and leased lines for business users. Meanwhile, the Internet has been developed from the beginning for best-effort services (i.e. each IP network gives its best effort to transfer the IP packets through it) and it is network neutral by nature (e.g. no differentia- tion of IP packets by Internet service providers (ISPs) regarding the source or destination address, application, or type of content carried by the packets). However, the approaches from both sides (telecoms and the Internet) have merged, including QoS support as the main contribution and requirement from the telecom side (e.g. for real-time services, such as voice and TV) to influence the initially best-effort and network-neutral Internet. The convergence of all telecommunication services onto the 1 Introduction Table 1.4 General QoS terms [12]. QoS term Definition QoS requirements of user/customer A statement of QoS requirements by customers/users (QoSR) with unique performance requirements or needs. QoS offered/planned by service provider A statement of the level of quality planned and offered (QoSO) to the customer by the service provider. QoS delivered/achieved by service A statement of the level of QoS achieved or delivered provider (QoSD) to the customer. QoS experienced/perceived by A statement