Ephemerality is the concept of things being transitory, existing only briefly. Typically the term ephemeral is used to describe objects found in nature, although it can describe a wide range of things, including human artifacts intentionally made to last for only a temporary period, in order to increase their perceived aesthetic value. With respect to unique performances, for example, it has been noted that "[e]phemerality is a quality caused by the ebb and flow of the crowd's concentration on the performance and a reflection of the nostalgic character of specific performances". Because different people may value the passage of time differently, "the concept of ephemerality is a relative one".