Most Americans still get their news from television, radio, newspapers and magazines, but that is changing, and more rapidly than you may think.

Reliable research tells us that four in ten adults in America these days get their news from Facebook and one in ten from Twitter. And those metrics are growing daily. For millennials — ages 18 to 35 — Facebook is, by far, their No 1 source for news about government, politics, the economy and the world, generally. It is indisputable that the number of Americans who now get their principal news from outlets such as Facebook, Twitter, Google, Instagram and other digital sources is multiplying dramatically.

This trend in news gathering is not going away.

Social-media companies routinely assert that they are not news organisations. They prefer to be known as news distributors or news aggregators. The news they carry is largely not originally reported, but rather aggregated from more traditional sources. To be sure, some of what now comes under the heading of news on some social media can be trivial and puerile. Think of all those cat videos or BuzzFeed’s bursting watermelons.

The internet rightfully boasts numerous highly professional news providers such as the websites of the nation’s leading dailies and network television as well as many basically internet-only sites such as Politico, The Huffington Post, Yahoo News and the newly launched BuzzFeedNews arm that will compete with the established online media outlets.

Social-media posts circulate from user-to-user in near real time and typically come from a known or “trusted” source. This is not “trusted” in the typical sense of a respected news source such as The Wall Street Journal or The Washington Post, but in the sense the news or message comes from a fellow member of the reader’s social-media network, such as Facebook, LinkedIn, Twitter, etc. The credibility or reliability of the source is left to the reader’s personal judgment and experience.

Nonetheless, whatever their formal self-identification — “mere pipelines” — the men and women who have created social-media platforms have built on the unique advertising value of such an engaged young audience plus the font of information they have about them and their personal tastes.

News aggregators provide their users with links to the original news sources. Google News is a very popular example. Why visit a half-dozen actual news sites when Google will aggregate links to all reportage on a given story or topic? The links provided by Google invariably take the reader back to the news site that created the content. In some way, this expands the actual readership for the originating news organisation and adds visitors to its news site, which will in turn beef up its advertising base.

Many high-end news providers limit what a non-subscriber may access. For example, a user trying to access content may hit a paywall that limits user access to the story. A subscriber will be given an opportunity to log in and to access the full story. Different news sites have different ways to limit access. The online version of The Wall Street Journal, for example, will provide a brief teaser consisting of the headline and a paragraph or two. Only WSJ subscribers can see the full story.

Different news organisations use different variations. Some news sites limit user access to a given number of stories per month; some offer access to breaking news but charge or require a subscription to access news archives; other sites offer only a subscription option; some provide trial subscriptions — and there are other mixed variations as well.

Taken as a whole, traditional news organisations are still experimenting with ways to ensure that users pay for content. All of these online subscription models amount to efforts by news providers to evolve a model that will allow them to pay their news-gathering staff and to cover overhead cost. A few news organisations are also actively experimenting with business models that combine advertiser-created content along with traditional reportage. The advantage of news being disseminated through social networks is the speed at which the information gets from the content creator to the consumer. It creates a new instant global network, but this also comes with dangers. The information and those providing it do not have to be verified and may not disclose personal biases. Online, there are no fixed standards or rules for covering and writing about newsworthy topics. Assessing credibility is left to the reader.

This issue of integrity is clearly a challenge for online news networks such as The Huffington Post, BuzzFeed and Politico, and with online advertising dollars at stake on social-media sites, there is concern that social-media sites could be using their platform to give preferential treatment to specific stories or topics.

In fact, Facebook recently issued a 28-page document called Trending Topics, in which the company details criteria that its editors and algorithms use to select and to prioritise the news they aggregate.

Going forward, one consequence is certain: as more and more young readers come of age and the older population passes from the scene, the business of reporting news will continue to change, with social media being the prime mover.

This is a very significant development that will be watched and commented on by many, ranging from lawyers anxious to protect their clients to Congress prepared to provide oversight.

Journalism schools today recognise this reality and are instructing students accordingly.

The day is not too far off when social media establishes itself as a primary source for what is happening in the world for the largest segment of news readership.

This, regrettably many believe, also has a toxic downside. Social media has, for better or worse, produced a phenomenon that has been labelled “citizen journalism”.

Anyone, anywhere, anytime, however disreputable and offensive their opinions may be, have a medium to give voice to pernicious views. Of course, some will defend such a development as a positive, desirable extension of free speech and democracy, although that is rejected by the vast majority of thinking people. Expect to be exposed to the most extreme ideas and philosophies. Recognise, too, that the dissemination capabilities of social media from a global, geopolitical perspective have a deeply negative aspect. Sophisticated strategists at Isis have used social media as a powerful recruiting tool, luring thousands of young Muslims from around the world to join its ranks.

All that noted, the dominance of social media among younger people has enormous implications for a democratic society and, very specifically, for corporate communications where organisations are seeking to reach and to influence the behaviour of people under 35.

In the new arena of social media, the walls between editorial and advertising that traditional media long established, have, to all intents and purposes, disappeared on social media. Now, algorithms largely decide upon news and advertising content.

The low barrier of entry for creating news content also has an upside. With tools such as cameras, and the platforms to share text, photographs and video easily accessible, events have been captured and shared in real time. Because of the speed of social media, events such as the attacks in Paris and Brussels, as well as the recent attack in Orlando, were first reported on online and were used by traditional media as a source of images and information.

Social media does not generate news in the traditional understanding of news, but it remains a powerful outlet that all corporate communications professionals should use to the advantage of their clients and employers. These platforms have become a hot new source for marketers making their advertising dollars go much farther than previously. Professionals must also recognise aspects of this new environment, including the ability to block adverts, and be prepared to deal with them.

It should also be pointed out that in this newer universe, in addition to getting much more precise data about the audiences they are seeking, marketers will be able to more effectively combine advertising with editorial matter. This so-called “native advertising” is an opportunity not to be ignored.

• Robert L. Dilenschneider is the founder and principal of the Dilenschneider Group