Abstract: A user-adaptive audio and/or video presentation system contains a background sub-system for presenting audio and/or video items, control for the background subsystem as regarding an actual selection sequence amongst the items according to a user preference pattern, and output means for physically presenting selected items to a user. Each item has a uniformly structured first set of static attribute data and associated second set of weight value data, and a third set of dynamic behaviour data. The dynamic behaviour of the items is collectively governed by behavioral and interactivity prescriptions, so that each respective item represents an autonomous agent. The control includes processing for under influence of the first and second sets of data and as governed by the prescriptions, updating weight and dynamic behaviour parameter data of each item versus other items for subsequently influencing the controlling.