In recent years, the notion of Quality of Experience (QoE) has gained increased attention to represent the quality of a service as it is perceived by the users. Accordingly, QoE amalgamates service integrity quantified by conventional\linebreak Quality of Service (QoS) parameters with non-technical but subjective factors. In this paper, we provide a survey on the evolution of QoE concepts in multimedia systems touching on the past, present, and future aspects. Specifically, the ideas behind QoE are discussed and an overview of related standardization work is provided. On this basis, QoE metrics for speech, image, and video are described. An outlook of future work and challenges is also provided.