Media playback is unsupported on your device Media caption White supremacist Richard Spencer: 'Donald Trump's arrow is pointing in our direction.'

The populist rhetoric of Republican presidential candidate Donald Trump has energised a disparate American movement that is accused of racism, anti-Semitism and misogyny.

Before Trump came along, Alex Jones was the great white hope for an army of disillusioned Americans.

The radio presenter's rasping delivery may be hard on the ears but for his fans it's food for the soul.

On the fringes of the Republican National Convention in Cleveland this summer Mr Jones was mobbed like a pop star after barking that he had given his enemies a "giant red, white and blue middle finger."

It was typical of the rhetoric from a man who came to prominence as a propagator of conspiracies, most controversially suggesting that the United States government was complicit in the destruction of the World Trade Center in New York City on 11 September 2001.

Image copyright Getty Images Image caption Alex Jones is one of the country's leading conspiracy theorists

These days the star of infowars.com is a brash and boisterous defender of Mr Trump, and his advocacy has helped to deliver to the Republican candidate a group of supporters identified as the alternative right or, more commonly, the alt-right.

This relatively new political movement is popular predominantly with young people. It is amorphous and difficult to define but on the whole its adherents tend to reject both left-wing ideology and mainstream conservatism.

Liberty, free speech and the right to offend are its touchstones. Opponents call it racist, misogynist and anti-Semitic.

"You can define it very, very broadly," says one of its key figures, Milo Yiannopoulos, who argues that it includes "classical liberals, disaffected leftists" and "ordinary conservatives" along with perhaps its most important element, a "youthful contingent that has suddenly become interested in politics again."

"Donald Trump has re-energised those people," he says.

Image copyright Getty Images Image caption Twitter banned Milo Yiannopoulos

During the US primary season some of the alt-right's supporters were fans of Hillary Clinton's democratic socialist opponent Bernie Sanders but, in an election which has roiled the United States like never before, Mr Trump now appears to have a claim on their loyalty.

The movement itself is a 21st Century phenomenon, characterised by the use of humour; online chatrooms; and the production and dissemination of cartoons or other images and ideas which take on a life of their own, becoming, in the parlance of the times, memes.

Because the alt-right manifests itself primarily online, estimating its strength is difficult.

Media playback is unsupported on your device Media caption 'Alt-right is unstoppable,' says Milo Yiannopoulos

It is also imbued with contradiction. Its adherents insist that they champion free speech but they tend to bristle at the slightest criticism and are frequently accused of behaving like "trolls" by descending, virtually, on critics and observers with sexually explicit insults and vicious threats- often anti-Semitic - apparently in an attempt to silence through intimidation.

"We're mischievous", they say when challenged. "So what?"

Mr Yiannopoulos is a case in point. One of the most charismatic and popular figures within the alt-right, the British journalist who works for the conservative website Breitbart News was banned from Twitter in July.

In a statement at the time, the social media company said "no one deserves to be subjected to targeted abuse online, and our rules prohibit inciting or engaging in the targeted abuse or harassment of others".

Image copyright Reuters

The man himself insists the right to offend is central to the freedoms for which the United States stands.

"We talk about free speech in very abstract, loose terms in Europe. Nobody really cares about it that much because we don't really have it. In America they do care about it."

The first amendment to the US constitution, which guarantees the right to free speech is, he argues, "the fundamental underpinning of American civilisation" and "it is under pretty grave threat".

The threat, he says, comes from "the progressive Left, feminism, Black Lives Matter," along with "the 'safe space' and 'trigger warning' culture" on college campuses and a media which attempts to narrow and constrain opinions, particularly of those on the right.

A Twitter ban has not silenced Mr Yiannopoulos who has spent the final stages of the campaign for the White House on a tour of American universities, some of which have gone to considerable, and arguably counter-productive, efforts to stop him from addressing their students.

More on alt-right

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Or read more: Trump’s shock troops: Who are the ‘alt-right’?

At a recent rally at the University of California, Irvine, some but by no means all of the students who packed in to a lecture theatre to hear him speak - mixing jokes about Hillary Clinton with attacks on Islam, globalisation and feminism - identified themselves as being part of the alt-right.

Several talked of feeling demonised as young, white men. The movement, they seemed to suggest, offered them a refuge for an identity under attack in a multi-cultural world where women were calling the shots.

Jason Garshfield, seated near the front, had draped the United Kingdom's flag around his shoulders.

"It's in honour of Nigel Farage and Brexit," he explained, "that's something that's very inspiring to us as Americans, that Britain could stand up to a group of unelected bureaucrats and we hope to do the same thing here."

The establishment of the Democratic and Republican parties, he said, had proven itself to be out of sync with the will of millions of Americans.

"They're losing power," he said, "and now we're starting to see a backlash across the western world… it's happening all over Europe."

There were similar sentiments among protestors at a recent demonstration outside CNN's bureau in Los Angeles, some of whom said they too identified with the alt-right.

US election: The essentials

"The only people that still believe CNN are the mindless sheep that are being poisoned by the food and the pharmaceuticals in this country. We've woken up! We see the truth," said Margaret Schofield, in between hollering through a megaphone at passing traffic on Sunset Boulevard about the merits of Mr Trump.

These themes - hatred and distrust of the old media giants and a belief that the establishment is using extreme and nefarious measures to keep the populace compliant - are common on alt-right message boards such as 4chan and 8chan, the latter of which has been removed from Google's search results and proclaims on its home page: "Welcome to the Darkest Reaches of the Internet".

On these sites, one image pops up a lot. It is a cartoon frog, Pepe, a character from the comic book Boy's Club who has been appropriated by the alt-right.

"It's really bad news," Pepe's creator Matt Furie told the BBC. "He's hanging out with the wrong crowd."

Jewish civil rights organisation The Anti Defamation League (ADL) is particularly concerned about the anti-Semitism on display on these message boards. In one notorious image, Pepe's original catchphrase "Feels Good Man" was changed to "Kill Jews Man". In others he wears a Nazi uniform.

Such images have prompted the ADL to designate Pepe as a hate symbol alongside the swastika and the burning cross, to the shock of Mr Furie.

"That was really surreal for me… the worst case scenario," says the cartoonist, who was subjected to online abuse and nasty emails after speaking out about the alt-right. Still, he is dismissive of the movement.

"They're what I would call trolls - and trolls on the internet don't have any objective except to just mess with people," he says.

Mr Furie says the best course of action is to ignore them - but he can't say the same for Mr Trump, whom he accuses of whipping up hatred among the alt-right.

"I think he's dangerous and I hope that he's not elected because I'm very scared of nuclear war," he says.

The Republican presidential candidate's rhetoric and his embrace of an anti-globalisation, anti-immigrant, nationalist agenda "has certainly resonated with the alt-right," says Joanna Mendelson of the Anti Defamation League.

Image copyright Getty Images Image caption The Trump campaign has denied using anti-Semitic language

She calls the alt-right a "virulently anti-Semitic" and "white supremacist" network advocating "intolerance and racism".

"There is an animosity, a racism, an upheaval that has grown and developed within this last year... and the alt-right is capitalising on that anger."

"They feel that white identity and white privilege is at risk," says Ms Mendelson.

Mr Yiannopoulos rejects the notion that he, personally, is a white nationalist.

"All my boyfriends are black," he tells the BBC. "I don't give a toss about skin colour."

He does care though, he says, about the "terrifying" and "regressive" social attitudes of Muslims in the West.

Image copyright Reuters Image caption The Make America Great Again hastag with a Pepe picture

So what of the future for the alt-right, especially if Hillary Clinton becomes the next US president?

"We're constantly told by the media that this will die with Trump," says Mr Yiannopoulos. "Couldn't be less true," he adds quickly.

"With Hillary Clinton in the White House they're going to be hugely energised. They're going to be angry. They're going to be louder than ever and they're going to start winning converts from her side," he says.

Ms Mendelson of the ADL uses strikingly similar language for her prognosis about the alt-right if Mr Trump loses.

"They still have revolutionised their base," she says. "There's momentum. There's anger. The alt-right is just going to capitalise on this. The revolution has already begun according to them."

And Mr Yiannopoulos insists that the alt-right is here to stay, irrespective of the election result.

"There is no way," he says, "that this movement, this huge nationalist, populist uprising against the nannies, against the globalists, against all of the massed ranks of the global elites, there's no way it's going anywhere."