LONDON — With days to go before the U.K. heads to the polls on December 12, all the traditional political parties — and lots of third-party groups — are doing all they can to woo would-be voters online.

Digital attack ads against their opponents. Spreading potential misleading facts on social media. Even slightly cringeworthy parody videos of "Love Actually."

So far, partisan groups have spent more than £2 million on digital campaigning ahead of Thursday's vote, a figure that will likely exceed what was spent the last time the U.K. went to the polls in 2017.

After holding back somewhat in the first few weeks of the campaign, the Conservatives are now turning everything up to 11 with a major outlay on Facebook political ads in a rerun of the Leave campaign strategy ahead of the Brexit referendum in 2016.

In response, non-affiliated actors (though often with ties to some of the political parties, notably Labour) are also spending big in the final days to counter some of the Conservatives' messaging. Much of that focuses on either anti-Brexit ads or calls for people to vote tactically to keep Boris Johnson out of No. 10 Downing Street.

Here's what you need to know:

What are these ads and who are they targeting?

Roughly 80 percent of online politicking is done on Facebook (and the company's other services like Instagram and Messenger). The company allows political groups to use its massive dataset of users to pinpoint messages — based on gender, demographics, socio-economic factors, or all of the above — to groups of people across the country.

That's particularly true in close-run races where political parties have tailored ads around specific local issues like the closing of a police station or investment in a nearby hospital.

How is this different from leaflet campaigns?

It's definitely true that social media advertising isn't much different from the decades-old practice that saw local parties mine the U.K.'s electoral register of voters to send pamphlets through people's letterboxes.

What is different is the scale, and in particular the cost of reaching that scale. With a few hundred pounds, anyone can create and distribute partisan messages to different voters across a single constituency — or across the whole country — with a speed and accuracy that makes old-school leaflets look like they're from the dark ages.

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What types of messages are the political parties promoting online?

It's much the same as offline politicking. The Conservatives have focused primarily on their pro-Brexit stance, with attacks on Jeremy Corbyn, the Labour leader. Interestingly, they've struck a more update upbeat note on Johnson's own Facebook page where the messages are both more positive and aimed at younger voters.

By contrast, Labour is talking about anything other than Brexit. Initially, the priority was to attack the Conservatives and their record in government. But in recent weeks, the tone has shifted to the party's own priorities, like its planned investment in the National Health Service.

For their part, the Liberal Democrats went at full pelt with their promise to scrap Brexit. But when that message didn't strike a chord with voters, the party's Facebook ads shifted to claim that only the Liberal Democrats could stop the Conservatives from winning an outright majority.

Is Russia meddling in the digital election?

There's no evidence of any foreign interference, either through divisive paid-for messaging on Facebook from unknown (possibly foreign) groups or elsewhere. That doesn't mean it's not happening, it's just that linking such tactics directly to the Kremlin or other governments is maddeningly difficult.

But what is true is that leaked documents between U.K. and U.S. negotiators around a possible post-Brexit free-trade deal did get onto the web in what increasingly looks like a Russian-style operation.

What is the government doing about that?

The security services are looking into it, but we won't know exactly what happened until months, if not years, after the election.

More troubling, successive governments haven't updated the country's electoral rules in response to the growth of digital electioneering, meaning a lot of what goes on online is either unknown, misunderstood or out of regulators' hands.

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