RTÉ Radio is a department of Irish national broadcaster Raidió Teilifís Éireann. RTÉ Radio broadcasts four analogue channels and five digital channels.

The first voice broadcast of 2RN, the original radio callsign for RTÉ Radio 1, took place on 14 November 1925 when Seamus Clandillon, the 2RN station director said, 'Seo Raidió 2RN, Baile Átha Cliath ag tástáil', Irish for 'This is Radio 2RN, Dublin calling'. Regular Irish radio-broadcasting began on 1 January 1926. Unfortunately, most Irish people could not receive 2RN's (1.5 kilowatt) signal. When faced with numerous complaints from Cork regarding the writers' inability to tune to the signal, Clandillon remarked in The Irish Radio Review, a magazine dedicated to the service, that they did not know how to operate their sets. 6CK was established in Cork in 1927; however 6CK was mostly a relay of 2RN.

All of RTÉ's stations are broadcast on mux 1 of the Irish digital radio system, as well as being streamed online.

A high power (initially 60 kW) station was established in Athlone, in 1932, to coincide with the staging of the Eucharistic Congress. 2RN, 6CK and Athlone became known as "Radio Athlone" or, in Irish, "Raidio Áth Luain" and were receivable across virtually the entire country. Radio Athlone became known as "Radio Éireann" in 1938.

Raidió Teilifís Éireann (Irish pronunciation: [ˈradʲo ˈtʲɛlʲəfʲiːʃ ˈeːrʲən] ( listen); English: Radio [and] Television of Ireland; abbreviated as RTÉ) is a semi-state company and the public service broadcaster of Ireland. It both produces programmes and broadcasts them on television, radio and the Internet. The radio service began on January 1, 1926, while regular television broadcasts began on December 31, 1961, making it one of the oldest continuously operating public service broadcasters in the world.

RTÉ is financed by a television licence fee and through advertising. Some RTÉ services are only funded by advertising, while other RTÉ services are only funded by the licence fee. RTÉ is a statutory body, run by a board appointed by the Government of Ireland. General management of the organisation is in the hands of the Executive Board headed by the Director-General. RTÉ is regulated by the Broadcasting Authority of Ireland. Radio Éireann, RTÉ's predecessor and at the time a section of the Department of Posts and Telegraphs, was one of 23 founding organisations of the European Broadcasting Union in 1950.

Radio is the transmission of signals through free space by electromagnetic waves with frequencies significantly below visible light, in the radio frequency range, from about 3 kHz to 300 GHz. These waves are called radio waves. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space.

Information, such as sound, is carried by systematically changing (modulating) some property of the radiated waves, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.

The etymology of "radio" or "radiotelegraphy" reveals that it was called "wireless telegraphy," which was shortened to "wireless" in Britain. The prefix radio- in the sense of wireless transmission, was first recorded in the word radioconductor, a description provided by the French physicist Édouard Branly in 1897. It is based on the verb to radiate (in Latin "radius" means "spoke of a wheel, beam of light, ray").

Tommy Tiernan (born 16 June 1969) is an Irish comedian, actor and writer. He and Hector Ó hEochagáin presented The Tommy and Hector Show on i102-104FM. Tiernan also featured in Father Ted as a depressed priest.

Tiernan was born in Carndonagh, County Donegal. His father is a native of County Kerry while his mother is from County Limerick. He moved, with his family, from County Cork as a child. After spells living in Zambia and London, he attended the same school as Irish television presenter Hector Ó hEochagáin and Dylan Moran, in St. Patrick's Classical School, Navan, Co Meath, a former Roman Catholic junior seminary. He later attended a boarding school, Garbally College, in Ballinasloe, County Galway.^{[citation needed]}

Tiernan has appeared several times on The Late Late Show. In the United States he has appeared several times on the Late Show with David Letterman. Recently^[when?] he appeared on the Michael McIntyre Comedy Roadshow, Lee Mack Show, DAVE's One NIght Stand and joined comedic legends Eddie Izzard and Ross Noble at Laughs in the Park.

Gabriel Mary "Gay" Byrne (born 5 August 1934; affectionately known as Uncle Gay,Gaybo or Uncle Gaybo) is a veteran Irish presenter of radio and television. His most notable role was first host of The Late Late Show over a 37-year period spanning 1962 until 1999. The Late Late Show is the world's longest-running chat show. His time working in Britain with Granada Television saw him become the first person to introduce The Beatles on screen.

From 1973 until 1998, Byrne presented The Gay Byrne Hour—later The Gay Byrne Show when it expanded to two hours—on RTÉ Radio 1 each weekday morning. Since "retiring" from his long-running radio and television shows Byrne has presented several other shows, including Who Wants to Be a Millionaire?, The Meaning of Life and For One Night Only on RTÉ One and Sunday Serenade/Sunday with Gay Byrne on RTÉ lyric fm. In 2006 he was elected Chairman of Ireland's Road Safety Authority. Since retiring he has become the "Elder Lemon of Irish broadcasting".

In 2010, The Irish Times said Byrne was "unquestionably the most influential radio and television man in the history of the Irish State". In 2011, he was approached to become President of Ireland but declined to run, despite topping opinion polls.