The BBC boasts 10 national TV channels in addition to regional U.K. programming, 10 national radio stations, 40 local radio stations and a website which averages 3.6 billion hits a month.
The BBC World Service broadcasts globally on radio, TV and online, providing news and information in almost 30 languages. The broader organization, meanwhile, cranks out TV gold such as science fiction series "Doctor Who" and long-running soap "EastEnders."
Its commercial arm, BBC World News, broadcasts 24 hours a day in more than 200 countries and territories.
HOW DOES IT DO IT — AND AT WHAT COST?
Most of the BBC's services in the U.K. are funded by a tax on households that have televisions or watch TV on computers or other devices, while profits from commercial ventures such as BBC Worldwide and BBC World News are used to invest in new programming and services.
Still, rival broadcasters in the past have complained that the BBC has used public money to fund types of programs supplied by commercial operators, ditching its public service mission in a quest for viewers.
Under pressure from critics to justify its 3.5 billion pound ($5.6 billion) budget in a time of austerity, the BBC in recent years has undergone a series of job cuts, cuts to operations and unpopular changes to employee pension programs.
Most of those changes were ushered in by Mark Thompson, who preceded Entwistle as BBC director general. Thompson is to assume the role of chief executive of The New York Times Co. on Monday, but faces questions over the BBC's decision to kill the "Newsnight" program on Savile — which occurred while he was still in charge.
PAST BBC CHALLENGES
The BBC has repeatedly faced off against the government over editorial independence.
Its first major confrontation was during the 1926 general strike, when Churchill unsuccessfully lobbied the prime minister to commandeer the airwaves because the strike limited the modes of communication between the government and the public.
The BBC later came under pressure to support a campaign in the Falklands in 1982, enraging the Margaret Thatcher government by casting doubt on official sources. The BBC's director general at the time insisted it needed to "guard its reputation for telling the truth."
In 2003, a BBC reporter suggested that then-Prime Minister Tony Blair had misled parliament with claims that Iraq had weapons of mass destruction. The government called for an apology, but the BBC refused. The BBC's source, weapons expert David Kelly, was named in the media and had to explain himself repeatedly. He later killed himself.
The inquiry into Kelly's death said the reporter had made "unfounded allegations" and called the broadcaster's editorial processes defective. The inquiry's findings led to the resignations of the BBC's chairman Gavyn Davies and its director-general, Greg Dyke — and the installation of Thompson as successor.
The broadcaster's charter sets out that "trust is at the foundation of the BBC: we are independent, impartial and honest." But public trust in the BBC has been declining for decades, according to polls, and the latest scandals are unlikely to help.
Entwistle may have quit, but observers say the BBC Trust, which ensures the broadcaster stays true to its public obligations, deserves scrutiny, too. Patten is expected on Monday to lay out plans for how to deal with the aftermath, and many expect more BBC resignations as the fallout spreads.
Kevin Marsh, a former senior BBC editor, says the broadcaster needs to get better at explaining itself and admitting its errors. Even if it never fully recovers, the BBC can probably "learn to live with" a new reality of weaker public confidence, he added.
Tim Davies, a former PepsiCo executive with a marketing background and no experience as a journalist, has been named acting director general. While BBC insiders might regard Davies with suspicion, "He doesn't have BBC blood flowing through his veins, and quite honestly at the moment that could be an advantage," Marsh said.