An independent review is to draw up proposals to ensure the survival of Britain's free press and tackle the growth of "clickbait" news online.
The review was launched by Theresa May in a speech in Manchester, in which she described the free press as "one of the foundations on which our democracy is built" and declared: "It must be preserved."
The closure of hundreds of newspaper titles across the UK in recent years was "dangerous for our democracy" because of the risk that voters will turn to "untrustworthy" sources for the information on which to form their views, said the Prime Minister.
The review will examine how the press is adapting to the new digital marketplace, including the role and impact of online platforms like Facebook and Google.
It will look at whether the journalistic organisations writing online content are getting a big enough slice of the income from online advertising in return.
And it will consider action to remove the commercial incentives driving the proliferation of "clickbait" stories, whose carefully crafted headlines attract large numbers of internet users to material of little or no journalistic value.
Culture Secretary Matt Hancock said a key focus of the review would be the regional and local press, after studies showed that two-thirds of local authority areas have no local newspaper.
The aim will be to ensure that the UK has "a vibrant, independent and plural free press", he said.
Mrs May said the development of digital media has had a "profound impact" on the newspaper industry.
Recent estimates suggest that the press earns only around £15 a year from each user of digital media, compared with £124 for those still reading print.
"Good quality journalism provides us with the information and analysis we need to inform our viewpoints and conduct a genuine discussion," said the Prime Minister. "It is a huge force for good.
"But in recent years, especially in local journalism, we've seen falling circulations, a hollowing-out of local newsrooms and fears for the future sustainability of high-quality journalism."
The closure of more than 200 local papers since 2005 was "dangerous for our democracy", said Mrs May.
She warned: "When trusted and credible news sources decline, we can become vulnerable to news which is untrustworthy."
The new review will look at different business models for high-quality journalism in national, regional and local press, and will recommend possible Government or industry action to improve the sustainability of the press.
An expert panel will be appointed within the next few months, with the aim of producing a report early in 2019.
The chairman of the News Media Association, David Dinsmore, welcomed the announcement.
"This review acknowledges the importance of journalism in a democratic society, the vital role that the press takes in holding the powerful to account and producing verified news which informs the public," said Mr Dinsmore.
"Viable business models must be found that ensure a wide variety of media are able to have a long and healthy future.
"Through digital platforms, news content is more widely consumed than ever before but the revenues to sustain the investment in that quality content are challenged. This review on a sustainable future is very welcome."