The wing or the thigh online dating
It was founded by privately educated, far-Left activist Jon Lansman and now claims 31,000 members and 200,000 supporters.
They have been hugely successful in using social media to mobilise supporters and change the face of political campaigning.
But they have also been dubbed ‘mob-mentum’ for their hostile online activity designed to prise out centrists.
In Brighton, a Momentum campaigner posted a video showing the faces of three Labour councillors superimposed on to dancing Orthodox Jews.
One abuser spotted the MP's social media posts announcing his and his wife's joy at learning they are expecting their first child, then told him on Facebook: 'Hope your baby dies.'The politician told The Mail on Sunday: 'All I did was to make a harmless joke.
It was clearly aimed at Mr Corbyn, not elderly people in need.'And the MP turned the tables on Mr Corbyn, saying that he should be 'called out' for the 'disgusting' abuse of his wife.'Labour, in effect, incited this.
Meanwhile, the MP questioned the conduct of Mr Corbyn, 68, after their Commons encounter.
The Labour leader demanded the Tory be 'called out' for heckling him over his age, with Mr Corbyn jabbing his finger in anger as he did so.
The Mail on Sunday has, in agreement with the MP, chosen not to name him or his wife to protect mother and child from further abuse.
Theresa May last night called for a halt to social media abuse and other threatening behaviour in politics, by all sides.
Speaking in response to the 'hope your baby dies' attack, and menacing posts against Conservative Brexit rebels, she told The Mail on Sunday: 'Threats of violence and intimidation are unacceptable and have no place in our politics.
Last night, a spokesman for Mr Corbyn said: 'Jeremy has always condemned abuse and personal attacks, whether online, in the Commons chamber or in the media.' Momentum is the Left-wing group set up just after Jeremy Corbyn became leader.
Acting as his loyal ‘Praetorian guard’ they have moved Labour to the Left, sidelining Blairites.