Compared to some media, radio is cheap to make and costs the listener little or nothing.
It is also a low-cost, easy and vital means of communication in times of emergency or natural disaster.
For people living in remote communities it's also a valuable source of information and entertainment and radio is particularly appreciated by those who cannot read or see.
Groups of people with little money in poor communities can crowd around a radio set and in some countries where women stay indoors, the radio is a treasured companion.
Many radio stations are now taking full advantage of opportunities created by broadband, mobile phones and tablets to enhance their offer.
Unesco backs plans to improve radio access to the estimated one billion people who are still unable to listen for various reasons.
Radio listenership is at a peak in France, with record audiences posted in 2013.
Figures show that 43.6 million people in France listened to the radio during a week in November-December, compared to 43.3 million during the same week in 2012.
However, although more people seem to be tuning in, they spend less time listening.
In 2012 the French spent an average 2 hours and 56 minutes compared to 2 hours and 58 minutes in 2012.
Peak listening times are in the morning and at the end of the afternoon.
Radio listening is unexpectedly popular in an age when newer media are competing for attention.
“A decade or so ago, we thought that podcasting would really develop considerably but it has more or less reached a limit now”, observes former RFI journalist Philippe Couve, who is now a consultant on media matters.
He also points out that some subscribers or organisations receive automatic podcasts of radio programmes but do not necessarily listen to them.
The biggest competitor to radio, according to Philippe Couve, is Youtube - especially among the under 35s.
He notes that this has led more and more music radio stations to create “visual radio”, putting cameras in their studios and providing graphics or video content.
While videos often go viral or create a buzz on Youtube, audio content rarely does. This could be changing, however, with the increasing popularity of SoundCloud, a sort of audio Youtube.
Of all the “traditional media”, radio has suffered the least from changing habits due to internet, and Philippe Couve maintains that listeners like the serendipity of radio. In an age when so much information is filtered or specially targets specific audiences, it appears that many people enjoy stumbling on new information or programmes while listening to the radio.
The growing success of radio has not gone unnoticed by the advertising industry. As television and the written press lose advertising revenue, it has gone up slightly for many commercially-funded radio stations.
In France, however, technological provision could still be improved. LTE technology has been available for less than a year and still only in some areas. Once this is rolled out countrywide, enjoyment of radio will be enhanced for those listening on mobile devices, who currently have to put up with erratic reception, especially while using public transport. France lags behind Britain and Germany in the provision of digital radio as well, while subscription-funded satellite radio, which needs significant investment to get started, is non-existent in Europe.