The document summarizes the history and development of portable audio devices from 1953 to present day. It begins with mobile radios in 1953, followed by portable stereos in 1962 and the Sony Walkman in 1979 which popularized portable music. Subsequent developments included the portable CD player in 1984, Mini-Disc players in 1992, MP3 players in 1998, and the rise of smartphones combining audio, internet and apps from 2001 onward. Current devices include dictation recorders and smartphones that keep users constantly connected through music and social media.