Quality of Experience is a measure of overall delight or annoyance of viewer's media streaming experience (ITU.T P.10 item 6.209). Many factors can impact QoE, including: poor PVQ, poor QoS, poor application performance. In contrast to QoS, QoE is an expression of the end-viewer's overall sentiment regarding the usage of a streaming service, and can include: the content consumption itself, e.g. picture quality (see Perceptual Video Quality), e.g. sound quality; as well as other aspects, e.g. inability to log into the streaming service, e.g. inability to browse the available video assets, e.g. content discovery producing irrelevant suggestions, e.g. UI / UX issues, e.g. same ad fatigue, etc. QoE can be impacted by QoS, e.g. packet loss (see Quality of Service) which, in turn, can impact PVQ, e.g. induce video macroblocking (see Perceptual Video Quality, a factor in QoE).