Ailsa Chang

The question of how Billboard determines the most popular music in the country has gotten a lot harder in the digital age. It used to be a simple question of which album sold the most physical copies, but now Billboard needs to consider things like Spotify plays and mp3 downloads. Starting Jan. 3, it will also include YouTube streams.

NPR's Ailsa Chang talks to Chris Molanphy, a chart analyst and pop critic at Slate, about the significance of this change. Listen at the audio link and read on for an edited version of their conversation.

Two witnesses testified during the last scheduled day of public impeachment hearings on Thursday. Fiona Hill, a former National Security Council official, and David Holmes, a political counselor in the U.S. Embassy in Ukraine, spoke in front of the House Intelligence Committee — wrapping up two weeks of public and closed-door testimonies to Congress about President Trump's actions in the Ukraine affair. Click the audio link to listen to a special broadcast of NPR hosts and reporters offering analysis on the significant moments of the day.

The former U.S. Ambassador to Ukraine, Marie Yovanovitch, testified in front of the House Intelligence Committee on Friday in the public phase of the impeachment inquiry. Click the audio link to listen to a special broadcast of NPR hosts and reporters offering analysis on the significant moments of the day.

As a kid, Enrique Olvera spent hours in his grandmother's bakery in Mexico City. He loved watching everyday ingredients like flour, sugar and eggs fuse into something entirely different.

For Olvera, even the simple act of baking a cake felt like magic.

He absorbed every detail as his grandmother gently coaxed masa into handmade tortillas. On Sundays, he joined his father in the kitchen, chopping onions and tomatoes for breakfasts of scrambled eggs and dry beef.

Lt. Col. Bree "B" Fram left a doctor's office on April 2. Presenting that day as Bryan, the name given to them at birth, B should have been relieved.

"Overall, it's a good thing," said B. "It just didn't feel great to have to do it on someone else's timeline other than my own."

"It" was an official diagnosis of gender dysphoria. As a transgender member of the military, B had to secure the diagnosis by April 12 in order to continue serving openly.

Quinn Robinson is only 18 years old, but she has already learned some hard lessons about the world. "It's scary being a trans person because I know there are people out there who just hate me for being myself," she says. "There's been kids who have approached me and say, 'Hey, you should burn in hell.' "

Robinson is a high school senior in Allendale, Mich., a small but growing town about 30 minutes outside Grand Rapids and smack dab in the middle of what's known as the state's "Bible Belt." Drive off the main road and you quickly find yourself in farm country.

The new movie If Beale Street Could Talk is based on a James Baldwin novel of the same title.

Barry Jenkins (Moonlight) adapted and directed the film. And in working with the Baldwin estate, he received a leather notebook filled with Baldwin's handwritten notes about how he would have approached a film version.

Tayari Jones says there are two things to consider as a book matchmaker: "You have to match what you think your friend would like to read, with what you think your friend should read — and you have to make a Venn diagram of that," she says.

Cooking is about community. But it can also be about solitude.

That's where chef Anita Lo's latest cookbook, Solo: A Modern Cookbook for a Party of One, comes in.

"Food is culture, food is identity. So it's reaffirming to cook the things that either you grew up with or the things that you love," Lo says — whether it's for your whole family or just yourself.

Last year, NPR Music picked the 150 greatest albums made by women for the first year of the Turning The Tables series, an ongoing project dedicated to recasting the popular music canon in more inclusive ways.

President Trump has a heaping plate of foreign policy background to consume in May, which will see a possible summit with the leader of North Korea, a deadline to decide on restoring Iranian sanctions, and the move of the U.S. Embassy in Israel from Tel Aviv to Jerusalem.

In the past, most presidents have leaned on the intelligence community for guidance and context — but Trump has made plain his differences with the CIA, FBI and National Security Agency.

In jails and prisons across the United States, mental illness is prevalent and psychiatric disorders often worsen because inmates don't get the treatment they need, says journalist Alisa Roth.

In her new book Insane: America's Criminal Treatment of Mental Illness, Roth investigates the widespread incarceration of the mentally ill in the U.S., and what she sees as impossible burdens placed on correctional officers to act as mental health providers when they're not adequately trained.

In 1993, Alex Wagner saw a familiar face on the cover of Time magazine: It was a computer-generated picture of a multiethnic woman who reminded her of ... herself.

Wagner's father is white and from the Midwest; her mother is from what was then Burma. And after reading the Time story on "The New Face of America," Wagner, then a teenager, decided to embrace her identity as a "futureface."

A couple of years ago, Bernie Dalton was a strong, physically fit, 40-something-year-old surfer. Every morning, he would get up at 4 A.M. to watch the sunrise in Santa Cruz, Calif. Bernie wasn't a musician at the time, but he was passionate about music. His lifelong dream was to record an album.

Friday is April 20, a day that some people celebrate by smoking marijuana. The Police Department in Lawrence, Kan., is preparing for this week's pot holiday by sending safety tips via their official Twitter account, run by officer Drew Fennelly.

A sports editor at The Kansas City Star retweeted it, and Fennelly says it became the account's first tweet with national reach.

"It ended up getting a couple thousand likes, over 1,000 retweets," he says.

Desiree Linden became the first American woman to win the Boston Marathon since 1985 — finishing 26.2 miles in 2 hours, 39 minutes and 54 seconds on Monday.

The 34-year-old two-time Olympian lives in Michigan, and she finished second at the Boston Marathon in 2011. But her victory this week almost didn't happen.

In the cold rain and wind, Linden says she wasn't feeling well and thought about bailing out of the race.

The Flushing neighborhood of New York's Queens borough is home to the largest population of Chinese immigrants in any city outside Asia.

Zhuang Liehong is one of those immigrants. He arrived in 2014 from Wukan, a small village in the Guangdong province of southern China.

When he first arrived in Flushing, he says it felt like a city in China.

"Other than the buildings and Chinese store signs, just look at the pedestrians on the streets," he says. "They're mainly Chinese people."