Ultra wideband, commonly known as UWB, is an emerging wireless personal area network (PAN) radio technology that is unique in that it can be used in communications, radar systems as well as in range and location measurements. Though UWB seems to be a new, trendy technology, its roots can be traced back to the 1960s. This paper describes UWB from the technological perspectives of its modern history, evolution and emergence. Its benefits, existing applications and future trends are also given here.