This book explores the history of ham radio operators, emphasizing their social history and their many contributions to the technological development of worldwide communications. It traces the concept of relays, including the American Radio Relay League, from contacts as close as 25 miles apart to operators anywhere in the world. The book highlights the part played by ham radio in many of the headline events of the half century, especially exploration and aviation "firsts". The ways in which these primarily amateur operators assisted in times of disaster including such events as the sinking of the Titanic and the 1937 Ohio River flood, are also examined.