Attributes
An attribute is a characteristic of a concept*. If we had the concept of a Hand, for example, an attribute might be number of fingers. If the concept was Fish, an attribute might be length.
Continuing with the music festival example, an attribute of an Event might be Start Date. Another could be End Date. An attribute of a Location might be Latitude and another Longitude. A City migh have a Population attribute, and so on.
*An attribute is equivalent to a Datatype Property in OWL.