On Saturday, Jeremy Corbyn was elected leader of the British Labour Party, causing a small implosion in the world of English politics. Thing is, Corbyn was unknown to almost anyone, even within his own party, before he won his position in a landslide victory. And he comes from a previously mocked fringe.

So, who is Jeremy Corbyn, why is his rise to power such a shocker for the United Kingdom—and why should Americans care?

Who is Jeremy Corbyn?

Corbyn is a member of Parliament (MP) for the London constituency of Islington North and a massive socialist (the extreme type conspiracy theorists think President Barack Obama is, not the social democratic type Sen. Bernie Sanders (I-Vt.) actually is). Corbyn actually advocates full-on, permanent, worldwide revolutionary socialism. Age 66, he is one of the oldest party leaders in recent history. Until now he had been on the fringes of the Labour Party ever since first being elected to Parliament in 1983, and he was often the notorious rebel against his own party’s direction on voting. Except, as of Saturday, he now runs that party.

https://twitter.com/ThisBrightFlxsh/status/642651010490585088

How did Corbyn win the election?

After the general election in May, when Prime Minister David Cameron’s Conservative party was returned to a majority government, the leader of Labour, Ed Miliband, resigned after failing to convince the public to back his social democratic policies.

As a result, the party had to find a new leader. This is chosen by a nomination period, whereby the party’s MPs choose who they want to go to a members ballot, with a minimum of 35 nominations required. Corbyn achieved the required number just minutes before the deadline in July, after other party members decided to nominate him to “broaden the debate” within the party. He eventually won after the 3-month-long campaign, mainly due to his ability to catalyze support and young voters through social media and trade union engagement.

when you realise you and your nomination to 'broaden the debate' are responsible for this disaster#labourleaderhsip pic.twitter.com/fGunZVkCh6 — Tom Harwood (@tomhfh) September 12, 2015

What’s different?

Remember Tony Blair? Blair promised “a new dawn” for Labour, and he managed to take them to their most successful election victory in 1997, turning over 18 years of Conservative government. He followed on to win two more elections, and invade four other countries, before stepping down in 2007. Blair’s politics were a far cry from the socialism advocated by Corbyn, and it was thought that Blair’s ideals were the only possible future for Labour, especially after Miliband, who is slightly more left-wing than Blair, lost in May.

While Blair supported private ownership of industry over nationalisation, Corbyn is all in favor of the latter. There are other differences, but that helps show there is quite a gulf between the Labour Party of Saturday morning before Corbyn’s victory and the one of Saturday afternoon.

Is he at least funny?

Prepare for years of seriousness. Corbyn apparently doesn’t like jokes. In fact, to make up for his lack of humor, an entire Twitter account makes his jokes for him, which Corbyn is very grateful for.

My wife went out drinking with Fidel Castro's wife.

Tequila?

No, you're thinking of the CIA. — @corbynjokes (@corbynjokes) August 22, 2015

He’s also become somewhat of an Internet character, with his own fandom.

The man’s dress sense has also come under quite a lot of scrutiny. Corbyn eschews dark suits and ties and instead opts for a style crossing communist chic with beige tones that were last worn in the 1970s, a time that he would probably like to return to.

Why is Jeremy Corbyn dressed like an extra from the Sk8er Boi video? pic.twitter.com/t8j8ntczFu — Jamie Ross (@JamieRoss7) September 11, 2015

He also received some love from Donald Trump, who accidentally retweeted a picture of Corbyn thinking it to be a fan’s relative. Something he’s done before, except with serial killers.

"@HamishP95: @realDonaldTrump My Dad is thinking of voting for the first time ever for you. http://t.co/1u9qi8qUPc" Great. — Donald J. Trump (@realDonaldTrump) September 12, 2015

What skeletons does he have in his closet?

Corbyn gets on famously well with Britain’s enemies. In the past, he has supported the IRA, Hezbollah, and Hamas. He also went on Iranian state TV and called the death of Osama bin Laden a “tragedy.”

https://twitter.com/DaveMorgan25/status/642763139038248960

Why should I care? I’m American.

Because it might mean the U.S. is in for a similar wild-card upset in 2016.

As Buzzfeed wrote this week, establishment candidates in the U.S. and elsewhere should have cause for concern. Corbyn was given 100/1 odds of winning by British bookmakers when he first declared candidacy. On Saturday, he won with almost 60 percent of his party’s vote, more than Blair in 1994. By the time Corbyn’s opponents began to realize the threat he posed to their election, it was too late to do anything. The closest thing to Corbyn in the current U.S. presidential field is Sanders, and the path he is following before the 2016 election is eerily similar.

Correction: An earlier version of this story incorrectly identified the number of countries Tony Blair sent troops to during his tenure as prime minister. The number is four: Iraq, Kosovo, Sierra Leone, and Afghanistan.

Illustration by Max Fleishman