Referring to a quality of service (QoS) level designed for applications that require transmission to take place in real time, that is to say that the transmission must take place at the exact moment and in the exact sequence as the event itself takes place in the real world. Real-time QoS is essential in many applications directly involving humans and their perception of time, and particularly those involving human-to-human interaction. Voice conversations and videoconferences take place in real time and demand real-time QoS. See also non-real-time, nrt, and QoS.