What is El Día de los Muertos, or “Day of the Dead,” as it’s now known in the U.S.?

Despite the white faces and the skulls, it's not meant to be a spooky holiday and it's not Halloween. Also known as Día de Muertos, the celebration originated in central and southern Mexico. Those who celebrate it believe that at midnight on October 31, the souls of all deceased children come down from heaven and reunite with their families on November 1, and the souls of deceased adults come visit on November 2.

Families make colorful altars in their homes in honor of their deceased loved ones, and the altars are decorated with flowers, candles, their loved one's favorite food and pan de muerto (a slightly sweet bread specifically made for this time).

File photo of an altar in Houston, Texas. Claudia Deschamps

The festivities continue in the cemetery, where families bring picnics, play music and sometimes even spend the night as a way to celebrate the lives of those who are no longer on this earth.

Related: What Is Día de Muertos? 3 Things to Know

The inextinguishable tradition dates back 3,000 years, during the time of the Aztecs. It survived through the 16th century, when the Spanish arrived to central Mexico and thought the tradition to be sacrilegious. Instead of it being abolished, however, the celebration evolved to incorporate elements of Christianity, such as celebrating it on November 1 and 2 instead of on its original summer observance to coincide with All Saints’ or All Souls’ Day, a time to pray for departed souls.

In San Francisco, California, Martha Rodríguez-Salazar has been working with the San Francisco Symphony for the past 10 years in their annual Día de los Muertos community celebration, which includes music and altars commissioned from different artists.

Dia de Los Muertos event at San Francisco Symphony. Marc Hors

“My parents never made an altar while I was growing up, but some of my friends did,” said Rodríguez-Salazar, a conductor, flutist, mezzo-soprano and teacher who was born and raised in Mexico. “Every November 1st and 2nd, they put altars of family and friends. In the Bay Area, it’s become sort of in fashion - its own thing — where people dress up. In Mexico, it’s not that way."

"Here is where you paint your face," said Rodríguez-Salazar. "Now with globalization, it’s mixing," she explained.

"The tradition [in Mexico] is you invite people to your house for pan de muerto and then you go to the cemetery. You eat food there, drink tequila or mezcal, and that’s the celebration. You want to leave your door open because a stranger can bring a spirit of your loved one. You never know.”

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Dina Leor's Mexican folk store in New York City has been busy selling items for altars to celebrate El Día de los Muertos. Almeida Photography / Almeida Photography

Dina Leor, owner of La Sirena Mexican folk art store in New York City, has been an avid celebrator of Día de Muertos since she was a little girl, and she’s not even Mexican.

“My mom is from Argentina and my dad is American — and my heart is Mexican,” Leor told NBC News. “I was around 11 when I first went to Mexico, and I fell in love with the country and culture; I feel so connected to it.”

RELATED: Día de los Muertos Altars: Loving Tribute to Deceased Family, Friends

Leor opened her store in 1999, and for 18 years she’s been bringing a bit of Mexico to NYC, from its colorful trinkets to its celebrations.

On October 21, she held a Dia de los Muertos pop-up market where she sold everything one needs to make an altar.

“I’d say 90 percent of the people who came were Mexican,” said Leor. “A lot of people were coming to buy stuff for their altars. Copál — resin to burn on the altar, and mini papel picados (paper cut outs), and the flowers made out of paper were best sellers.”

A woman uses a ladder to reach a niche during a cleaning of the graves at the General Cemetery, in preparation for the upcoming Day of the Dead festivities, in La Paz, Bolivia, Tuesday, Oct. 31, 2017. Day of the Dead or Dia de los Muertos is celebrated Nov. 1 and 2 to remember departed loved ones, many holding graveside picnics through the night. Juan Karita / AP

Leor was also asked to do another pop-up at the American Folk Art Museum in New York City, which celebrated Día de Muertos last Saturday.

“A lot of people were asking, ‘Is this Halloween?’,” Leor said about the visitors, mostly non-Latinos, who were passing by her stand.

“My tables looked like altars with papel picado, figurines, bark paper, and José Guadalupe Posada’s prints. This was introducing them to Día de Muertos. The museum wanted to have a Day of the Dead feel, not Halloween, and the woman who ran the gift shop brought pan de muerto.”

Leor said the celebration has always made sense to her.

File photo of a Dia de los Muertos celebration at the Hollywood Forever cemetery in Hollywood, California. AFP-Getty Images

“When I was 8, I made a space for my deceased grandmother and lit a candle for her, and left water for her, and I didn’t even know about Día de Muertos,” she said, but not everything was as natural. “Before I had my store, I was worried about having skeletons, and now I love them. I find them colorful and joyful."

Juan Castaño, co-founderof Calpulli Mexican Dance Company, moved to New York with his family when he was 22.

“I am a Mexican-American born in the border city in El Paso, Texas. My identity is both Mexican and American. Growing up, I knew about Día de Muertos, but it’s not something my family really did, since it came more from southern Mexico," he said. "When we moved to New York, I met people from Puebla, and I started learning more.”

Dancers perform at the Capulli Mexican dance Company's annual "Dia de los Muertos" production. Stefanie Delgado / Stefanie Delgado

When his father passed away, Castaño wanted to do something special, so he decided to make his first altar.

“It was really a beautiful experience...It’s a very personal thing,” he said. “I remember looking at the altar and putting coffee there, because my dad loved coffee. My mom said, ‘No, he would never like it like that — and she took it away and made it piping hot with a little sugar, and the experience created a conversation between us," said Castaño. Dia de Muertos is very powerful, because you feel peace and a beautiful experience remembering someone and celebrating what they did and who they were.”

His 14-year-old Calpulli Mexican Dance Company has always incorporated elements from Día de Muertos in performances that started on October 26th and will have a final performance on November 4 in New York’s prestigious Town Hall.

Related: Voices: On Día de Muertos, No Elaborate Rituals, Just Honoring My Dad

“The theme and the message of the story if what Día de Muertos is about — the hope that we have to reconnect with the loved ones we have lost," he said. "The world of the dead, according to Aztec mythology is called Mictlan - a beautiful world where we all want to be.”

Although they are separate celebrations, Castaño believes there has been a huge influence on Día de Muertos from the U.S. and Halloween, namely the face painting.

File photo of Joanna Tovar of Santa Fe Springs, Calif., applying a death mask makeup at a Dia de los Muertos (Day of the Dead) festival at Hollywood Forever Cemetery in Los Angeles. Reed Saxon / ASSOCIATED PRESS

“I think anytime cultures come together, it’s a way to bring communities together. In my opinion I don’t think it’s a negative thing,” he said. “I have nephews that love Halloween, but I think it’s really nice for them to know about Dia de Muertos, too — it's such a nice way to deal with death and celebrate death in a healthy, constructive way."

"For young people, the boogie man [and Halloween] can be traumatizing," said Castaño. "Maybe we can disarm the fear, stress and anxiety of what dying represents.”

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