The issue of fake news rose to the fore last year when then presidential candidate Donald Trump labelled reports from American established media outlets such as CNN and the New York Times as "fake news". Since assuming office, President Trump has continued to use the term "fake news" regularly and liberally, helping it gain currency in public discourse.

However, the term "fake news" is problematic, and many complexities lie beneath these two ostensibly simple words. For a start, news is meant to be objective reports of factual events, so fake news is by definition something of a self-contradiction.

The term "fake news" can be taken at face value to refer to news reports that are untrue, fabricated, and calculated to deceive. Yet the mind-boggling diversity of media platforms we access today has birthed many different forms of content that can be regarded as fake news.

Media scholar Renee Hobbs identifies six different types of fake news:

•Disinformation. This is false information produced with intent to deceive, such as Macedonian teens creating fake pro-Trump reports about the US election to generate online revenue.

•Propaganda. This is biased information manufactured to advance a political cause, such as terror group Islamic State in Iraq and Syria's use of online videos to recruit members.

•Hoaxes are elaborate montages of textual, visual and video content that contain sensationalist yet compelling messages aimed at tricking consumers.

•Satires or parodies refer to content that is deliberately made to resemble conventional media genres but conveys critical or subversive messages. They may employ sarcasm, humour or gross exaggeration, with American site The Onion and Singapore's New Nation being good examples.

•Inaccuracies in journalism are information which is incomplete, unverified, or simply erroneous.

•Partisan news is content that frames the message to favour the interests of particular individuals or entities so as to sway public opinion on particular issues.

Each of the above forms of fake news requires that media consumers marshal different combinations of knowledge and skills to discern the intention of the message and its source, so they can recognise when they are being misled or manipulated. But what cost does fake news exact on society?

Take the example of health scares such as those involving contaminated food or tainted medicinal products. Such hoaxes may take the form of a warning by a purported victim, accompanied by illustrative photographs or videos. The victim may caution against purchasing the product, and condemn the store that sold the defective goods. Individuals then share such posts via their social media network, such as Facebook, WhatsApp or Twitter, often with the proviso "not sure if this is true but just in case...".

Every person who shares that information is actually, unwittingly, party to that hoax, as he is helping to spread that information. That hoax gets a life of its own, attracting even more eyeballs when picked up by online news sources on the lookout for viral content to boost readership and advertising revenues.

Companies implicated in the hoax incur financial and reputational loss. Regulatory agencies have to step in to restore public confidence in food safety and public health.

Apart from such quantifiable costs, each hoax shared reinforces the social norm that sharing such "news" is the responsible thing to do. If permitted to take root, such practices exacerbate the problem of disinformation.

How then should society tackle the issue of the diverse range of fake news?

An approach that galvanises ordinary citizens, the public sector and corporate forces to work together to tackle disinformation is crucial. That is why, as amorphous and imprecise as the term "fake news" is, it has concrete value. A growing awareness of the problem of fake news has shone the spotlight on the pressing problem of disinformation.

Media literacy is widely regarded as the way to nurture more discriminating media consumers, by equipping them with competencies to recognise bias, fabrication and deception in media content. Long considered the preserve of educators, academics and policymakers, media literacy is increasingly seen as an essential competency that everyone - children, working adults, retirees - must possess. There is a need for public education in this area. Such education can give media consumers heuristics, or mental shortcuts, to recognise when media content is false or highly partisan, help them recognise the means used to manipulate media content, and sensitise them to the profit-driven motives of the purveyors of fabricated news.

The volume and sophistication of fake news are likely to rise, given the commercial incentives to create fake content to be shared virally, and given state actors' interests in pushing disinformation to target rival or enemy countries.

Platform companies like Facebook and Twitter will increasingly find it hard to verify the content they host. Even if these tech giants can harness resources to automate the detection of fake news, the judgment involved in distinguishing between content that is patently false and subtly partisan is best exercised by human readers.

For example, in the recent Indonesian election, Turn Back Hoax was a crowd-sourced effort where concerned citizens worked together to collect and debunk hoaxes spreading in social media. Indeed, a hybrid system that combines the agility of human judgment with the strengths of machine learning would be ideal.

As the Singapore authorities feel their way towards a legislative framework to combat fake news, they have to be realistic about the limits of what laws can do. The authorities need to work with the academics, and universities must work in concert with civil society to create a robust system by which members of the public can collectively refute disinformation that is gaining traction.

No arsenal of weapons against fake news is complete without a concerted push for a ground-up, crowd-sourced effort to call out fake news, and to get people to stop sharing information they can't verify.

For a start, social media users should pause before they hit "Share". If the source is dubious, verify first before sharing the information. If in doubt, don't share.

• Lim Sun Sun is professor of media and communication and head of humanities, arts and social sciences at the Singapore University of Technology and Design.