IP Quality of Service (QoS) models include Best-Effort, Integrated Service (IntServ), and Differentiated Service (DiffServ). Best-Effort is the default service model for the Internet, where all packets receive the same priority. Integrated Service is a model that provides end-to-end QoS guarantees in IP networks by reserving resources for specific flows. Differentiated Service is a scalable QoS model that differentiates traffic by classifying and managing it based on predefined policies. FIFO Service is not considered a QoS model.