S4C's headquarters are based in Carmarthen, at the University of Wales Trinity Saint David's creative and digital centre, Yr Egin.

S4C has been described by Elin Haf Gruffydd Jones [ca] as a "trailblazer" in European broadcasting for minority languages, going on air less than two months before Euskal Telebista (31 December 1982), TV3 Catalonia (test/trial broadcast on 11 September 1983, regular programming began in 1984) and Televisión de Galicia (24 June 1985), the first Spanish regional television stations to go on air, symbolically, in non-Castillan Spanish areas, and far ahead of other Celtic-language services, Ireland's TG4 (formerly TnaG) (31 October 1996), the ill-fated Scottish Gaelic TeleG (1999–2011) and BBC Alba (19 September 2008).

However, problems with transmission infrastructure and poor market research led to financial difficulties within two years, and after going bankrupt, the station was taken over by its neighbour Television Wales and the West.

[5] Shortly after the Conservatives won a majority in the election, the new Home Secretary, William Whitelaw, decided against a Welsh fourth channel, and suggested that, except for an occasional opt-out, the service should be the same as that offered in the rest of the UK.

This led to acts of civil disobedience, including refusals to pay the television licence fee, thereby running the risk of prosecution or even a prison sentence, and sit-ins in BBC and HTV studios.

[3] On 17 September 1980, the former president of Plaid Cymru, Gwynfor Evans, threatened to go on hunger strike if the Conservative government of Margaret Thatcher did not honour its commitment to provide a Welsh-language television service.

Future prospects for the channel were seen with little optimism, owing to the change in the DCMS funding method, with S4C receiving £100 million, attached to the Retail Price Index.

[3] As with other public broadcasters, S4C is facing the challenge of adapting to an increasingly mobile generation of viewers, coupled with competition from streaming services.

[13] S4C's former headquarters, which opened in 1991, were located at Parc Ty Glas Industrial Estate, Llanishen, following a move from Cathedral Road and Sophia Close in Pontcanna, Cardiff.

In March 2014, it was announced that Carmarthen was the winner with a bid led by the University of Wales Trinity Saint David (UWTSD).

UWTSD applied for funding for the building work and received £3m from the Welsh Government and a further £3m from the Swansea Bay city deal.

[19] In September 2018, S4C committed to ten years of lease on its Caernarfon office at Doc Fictoria (Victoria Dock), which has 12 full-time staff,[20] and was opened in 2008.

In January 2021 S4C's Presentation, Library, Promotion and Commercial departments moved to BBC Wales headquarters in Central Square, Cardiff.

The first programmes were broadcast from there on 27 January 2021, beginning with the channel's children's service, Cyw, at 6:00 a.m. Liz Scourfield's first live presentation aired later that morning, before the news bulletin at 12:00.

Like Channel 4, S4C does not produce programmes of its own; instead, it commissions programmes from BBC Cymru Wales and independent producers[23] (although the quantity purchased from ITV Cymru Wales has greatly reduced since the early years of S4C), and much like Channel 4 during its heyday, it has developed a reputation for commissioning animation, such as SuperTed, Wil Cwac Cwac (shown on ITV), Fireman Sam (also broadcast by the BBC), Rocky Hollow, The Blobs (also broadcast by Scottish Television), Gogs, Shakespeare: The Animated Tales, Animated Tales of the World and the 1992–1996 French co-production Natalie.

BBC Cymru Wales fulfils its public service requirement by producing programmes in Welsh, including Newyddion, S4C's news bulletin, and a soap opera, Pobol y Cwm, and providing them to S4C free of charge.

On the analogue service, S4C showed programmes produced for Channel 4 in the rest of the United Kingdom – either simultaneously or time-shifted – outside of peak hours.

Up until 2009, S4C ran its own teletext service, Sbectel ("Sbec", Welsh for "a peek" or "a glimpse", and a reference to an S4C schedule insert formerly included in the TVTimes issues for the HTV Wales region).

The programme that enjoyed the channel's highest viewing figures in 2022-2023 was Sgorio's coverage of Wales' UEFA Nations League match against Belgium in September 2022, which drew 456,000 viewers.

Following the switch-off of analogue terrestrial signals on 31 March 2010, Wales became the first fully digital region in the UK, with both S4C and Channel 4 becoming available to all homes.

[32] As a result, S4C now broadcasts solely in the Welsh language and, as well as on Freeview in Wales, is available throughout Britain, Ireland and the rest of western Europe on Freesat and Sky.

A review commissioned by the Department for Culture, Media and Sport in 2004 suggested that "S4C should operate a single core service after digital switchover".

In addition to the analogue TV signal transmitted throughout Wales, S4C, along with United News & Media, owned the company S4C Digital Networks (SDN).

[citation needed] On 27 April 2005, S4C sold its share of SDN to ITV plc for approximately £34 million, though it still has the half-multiplex as of right in Wales.

[42] It will broadcast for peak viewing hours only, from 7pm on weekday evenings and from 2pm on weekends, sharing capacity with the HD version of the BBC's children's service CBBC.

[3] On 7 September 1990, the new ident was introduced, depicting a piece of Welsh slate with colours blue, green, and red washing over the letters S4C until 31 May 1993.

The new branding, developed by the London-based firm Proud Creative, was intended to portray S4C as a more "contemporary" multi-platform broadcaster, and downplayed "traditional" Welsh imagery such as dragons.

[46][47] The magnetism-themed idents were later accompanied by a new set developed in collaboration with the agency Minivegas, consisting of live-action scenes with dynamic, animated elements that can react to the voice of the continuity announcer.

[51] In response, an S4C spokesperson stated that 90% of those programmes were aimed at pre-school children, and that BARB (the organisation that compiles television ratings in the UK) only takes into account viewers aged four years and over.

The remaining 10% consisted of repeats and daytime news bulletins which did not attract the minimum 1,000 viewers necessary to register on a UK-wide analysis.