Radio Broadcasting is the father of all broadcasting. The first experients with radio broadcasting as we know it started in 1905 and 1906 and then became available to the public from the 1920s onwards. One of the first radio broadcasts (including audio) was executed in the year 1906 by Reginald Fessenden. Fessenden transmitted him playing O' Holy Night on his violin and him reading Bible passages to ships at sea. He did this as his Christmas Eve broadcast.
The very first radio broadcasts were done in the late 1800s and were known a Radiotelegraphy. Radiotelegraphy wasn't able to carry audio signals as, to broadcast audio signals it required electron detection and amplifying devices.
The KDKA was the first commercially signed radio station in the United States of America.
Over the years radio has become more widely accessible to people who want to tune in.
in our current time we now have access to radio through AM signals, FM signals and now DAB (digital) signals. nowadays you will find that the newest cars come accustom with DAB capable radios fitted in them.
Radio is advancing and is adapting to new technology changes.