Ad targeting is how Facebook, Google and other online giants won the internet. It's also key to understanding why these companies are being held responsible for warping elections and undermining democracy, managing editor Scott Rosenberg writes in the opening installment of our "What Matters 2020" series.

• Critics and tech companies are increasingly considering whether limiting targeting of political ads might be one way out of the misinformation maze.
• Giant platforms would still allow campaigns and candidates to purchase political ads — but the companies would stop (either voluntarily or by law) selling messages aimed only at narrow segments of the electorate.

How ad targeting works: Facebook and Google have somewhat different systems for targeting ads, but both allow advertisers to bid on narrowly defined demographic groups or keywords.

• For instance, you can tell Facebook to show your message only to Southern men who don't have a college degree and earn less than $75,000 — or ask for married suburban moms in three ZIP Codes outside Indianapolis who own SUVs and play tennis.
• In the political ad world, these tools allow candidates and groups to exploit those populations' anxieties and resentments, efficiently.

The link between ad targeting and misinformation ... Tech platforms stand accused of multiple sins, including:

• Improperly collecting users' data to build massive databases of profiles.
• Allowing politicians and their campaigns to spread lies.
• Creating partisan "echo chambers" and "filter bubbles" that segment reality by ideology.

Facebook and Google didn't invent these phenomena — they existed pre-internet. But by tying them together, ad targeting can kick misinformation into overdrive:

• Data collection and profile building is what makes ad targeting possible. It's also what keeps getting tech platforms in trouble with users and governments.
• Campaigns have always shaded the truth and even lobbed false accusations. But in a broadcast world, it was easy for opponents and neutral third parties to witness and call out such behavior.
• In the world of micro-targeted ads, it's almost impossible — despite transparency efforts like Facebook's ad library.
• Misleading ads fuel frenzies in the closed-loop worlds of partisan echo chambers long before platforms can step in to bar them.

Banning all political ads vs. banning targeting: Many critics have urged social media platforms to bar political advertising altogether — a move both Google and Facebook have resisted, even as their smaller but politically high-profile competitor Twitter said it would embrace it.

• Facebook argues that such a ban would harm outsider candidates and causes.
• Twitter's ban is significant, but its ad market share and targeting capabilities are minuscule compared to Facebook's and Google's.

The idea of a targeting ban has gained momentum recently, with figures like Bill Gates and FEC chair Ellen Weintraub endorsing it.

• Defenders of the status quo argue that online targeting isn't fundamentally different from longtime campaign practices like ZIP Code targeting of postal flyers, and they maintain that it's a free-speech issue.

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President Trump blessed and helped win, against the odds, the Florida and Georgia governors races in '18 — an astonishing display of political muscle.

• This year, in two more conservative states, Trump tries a similar feat — Kentucky earlier this month, and Louisiana yesterday — and flopped. 

In Louisiana, "Democratic Gov. John Bel Edwards claimed a second term [last night], winning a stunning victory in a heavily Republican state and beating back repeated attacks," tweets and visits by President Trump, The Advocate of New Orleans reports.

• "Edwards defeated Republican businessman Eddie Rispone with about 51% of the vote, polling 40,341 ballots more than his opponent out of more than 1.5 million cast."

How it happened: "Urban ministers, organized labor and black politicians worked for Edwards, the 53-year-old who is the only Democratic governor in the Deep South," per The Advocate.

• "Rispone ... had Trump at his side at rallies — along with $2 million and 60 paid staffers sent at the last minute from the Republican National Committee and millions more dollars from the Republican Governors Association."

2020 Democrats are using Taylor Swift as political leverage against the private equity industry, after Swift publicly noted that The Carlyle Group had helped finance a deal whereby Swift lost control of her old master recordings, Axios private equity expert Dan Primack writes.

• Sen. Elizabeth Warren tweeted: "Unfortunately, @TaylorSwift13 is one of many whose work has been threatened by a private equity firm. They're gobbling up more and more of our economy, costing jobs and crushing entire industries. It's time to rein in private equity firms—and I've got a plan for that."
• Rep. Alexandria Ocasio-Cortez tweeted: "Private equity groups’ predatory practices actively hurt millions of Americans. Their leveraged buyouts have destroyed the lives of retail workers across the country, scrapping 1+ million jobs. Now they’re holding @taylorswift13’s own music hostage. They need to be reigned in."

Thought bubble from Primack: Private equity excess is a legitimate political issue, particularly when it comes to taxes and treatment of workers. But Warren and AOC are conflating those issues with what is essentially a contract dispute between a wealthy record label and its wealthy artist.

• Carlyle used no debt to acquire its stake in Ithaca, which represents a minority interest without operational control.

Go deeper (from Friday): "Taylor Swift escalates battle with ex-record label," by Dan Primack.

Pittsburgh Steelers quarterback Mason Rudolph goes after Cleveland Browns defensive end Myles Garrett, who's holding his helmet!

• Garrett ripped off Rudolph's helmet and bashed him with it during Thursday's game in Cleveland. (Browns won, 21-7.)

The result: One of the biggest melees in NFL history.

• Garrett, who was the league's No. 1 overall pick in 2017, must meet with Commissioner Roger Goodell before his reinstatement is considered, per AP.
• The NFL said Garrett "violated unnecessary roughness and unsportsmanlike conduct rules, as well as fighting and removing an opponent’s helmet and using it as a weapon."

"Pete Buttigieg has rocketed to the top of the latest Des Moines Register/CNN/Mediacom Iowa Poll," the Des Moines Register reports.

• "Since September, Buttigieg has risen 16 percentage points among Iowa’s likely Democratic caucusgoers, with 25% now saying he is their first choice for president."
• Why it matters: "For the first time, ... he bests rivals Joe Biden, Bernie Sanders and Elizabeth Warren, who are now clustered in competition for second place and about 10 percentage points behind."

The tale of the tape:

• Buttigieg: 25%
• Warren: 16%
• Biden, Sanders: 15%
• Klobuchar: 6%
• Booker, Gabbard, Harris, Steyer, Yang: 3%
• Bloomberg: 2%
• Bennet: 1%

When I dug into the N.Y. Times spread on the leak of internal Chinese government documents about the mass detention of Muslims, I found this insight into why President Xi Jinping has been escalating repression:

Xi is the son of an early Communist Party leader who in the 1980s supported more relaxed policies toward ethnic minority groups, and some analysts had expected he might follow his father’s milder ways ...

But the speeches [in the leaked documents] underscore how Mr. Xi sees risks to China through the prism of the collapse of the Soviet Union, which he blamed on ideological laxity and spineless leadership.

Worthy of your time.

The "Saturday Night Live" cold open imagined the impeachment hearings as if they were one of the soap operas they're preempting — "like tweets through a timeline."

• “I love the glamour and the spotlight," said the Marie Yovanovitch character, (Cecily Strong). "That’s why I spent my career in Ukraine and Somalia.”
• "Senate Majority Leader Mitch McConnell," played by Beck Bennett, drops in with a spoiler.

YouTube.