Lunar New Year falls on Jan. 25 this year, prompting more than 1.5 billion people around the world to celebrate with family and traditional foods.

While the customs vary between Asian cultures, the holiday marks the beginning of a new year on the second new moon after the winter solstice.

People of Chinese, Vietnamese, Korean descent — to name a few — often give children money and honor ancestors during the festivities of different lengths. In China, the Spring Festival lasts up to 15 days, while Vietnam's Tết Nguyên Đán goes for up to a week. Lunar New Year in South Korea, known as Seollal, runs for three days.

How does the Lunar New Year money-giving tradition work?

Ah, yes, those small red envelopes with cash inside. Called lì xì in Vietnamese or hóng bāo in Mandarin, adults give the packets to children in exchange for New Year greetings. Children typically receive envelopes from parents, grandparents, aunts and uncles, but sometimes receive from their parents' friends, too.

Chinese New Year:What does the year of the rat symbolize and more questions answered

The lucky money inside varies from $1 to several hundred and can reflect numbers of good fortune. The color of the envelope also bears significance, Yiju Huang, assistant professor of Chinese and comparative literature at Fordham University in New York, told The Indianapolis Star of the USA TODAY Network.

"Abundance is associated with the idea of redness," Huang said. "And the amount of money doesn't have to be a lot. It's such a tremendous joy for children, and they use the money to buy candies because they don't indulge in them usually."

In South Korea, parents give children New Year's money, called sebaedon, after children perform a traditional bow and wish them good fortune. The money is often put in silk or cotton pouches embroidered with designs.

What foods are especially popular for Lunar New Year?

For Vietnamese families, rice cakes called bánh chưng and bánh dầy symbolize the material and the spiritual, said Quyên Di Chúc Bùi, a Vietnamese professor at UCLA. Wrapped in dong or banana leaves, they contain sticky rice with meat or bean fillings.

First-person:Here's why Lunar New Year is significant, and how it's celebrated

"According to Eastern philosophy, the circle represents heaven and the square represents the earth," Bùi said. "So bánh dầy (round cake) symbolizes heaven and bánh chưng (square shape), symbolizes the earth. These two cakes represent the whole universe."

Other Tết Festival foods include roasted watermelon seeds and dried candied fruits such as coconut meat jam.

Chinese foods for Lunar New Year include longevity noodles for long life, whole chicken to represent family togetherness and sticky rice cake for prosperity. Some dishes feature word play in Mandarin, such as the rice cake called nian gao, which sounds like "high year," symbolizing a higher income and success.

'Bloated and icky':NYC restaurant owner promotes 'clean' Chinese food, gets blasted for racist stereotypes

In Korean households, a rice cake soup called tteokguk is the New Year's Day special. While it varies between regions, the broth is often made from beef and is garnished with egg, meat, dried seaweed and thinly sliced rice cakes. The white coin-like shape of the cakes symbolizes a prosperous year.

The traditional belief is after eating tteokguk, people turn one year older during Seollal.

What decorating customs are practiced during Tết and the Spring Festival?

People of Vietnamese heritage believe rearranging and decorating before the new year eliminates the worries of the old year, Bùi said. Vietnamese Americans in Orange County, California, home to the largest Little Saigon in the nation, practice the custom widely.

"Almost every family cleans their house clean and tidy to welcome guests in the first days of the year," Bùi said. "Law officers and doctors' offices, as well as service offices, restaurants and shops are all cleaning up in the hope that more customers will come in the New Year and the business will be more successful."

To welcome spring into the home, Bùi said families also place peach blossoms, chrysanthemums and ochna integerrima in the home. Their yellow, pink and red colors symbolize joy.

Chinese families also decorate with red during the Spring Festival, hanging up red lanterns, banners and signs. Displaying plates of "golden" citrus fruits such as tangerines and oranges is also believed to bring good fortune.

On front doors, people hang scrolls with black or gold Chinese characters featuring poetry about renewal, luck or success.

How do people honor their ancestors during Seollal?

In Korean tradition, families perform an ancestral rite called charye on the morning of New Year's Day. The ceremony reflects filial piety and gives thanks to family members who came before them, according to the Korean Cultural Center in New York.

Entire families gather in front of a table and set specific foods on it, such as tteokguk, noodles and grilled meat.

Looking for your roots?:For Asians, blacks and Latinos, DNA tests don't tell whole story

"Each type of food is placed in a specific order and direction," a booklet by the center says. "Once set, the rite begins with deep bows as greeting to the ancestor spirits, and proceeds with offerings and prayers before ending with bidding farewell to the spirits."

Some families wear traditional clothes called hanbok for the rite, while others dress in other formal attire.

Why does Lunar New Year fall on different days?

Because of differences between the solar-lunar and Gregorain calendar, which the United States follows. The Gregorian calendar is based on the Earth's cycle orbiting the sun, while the solar-lunar combines that with the moon's cycle orbiting the earth.

In major U.S. cities such as Los Angeles, New York City and San Francisco, events celebrating the new year take place in the weeks before and after the first day of the lunar year, which sometimes creates confusion.

The Lunar New Year typically falls between Jan. 21 and Feb. 20, so the holiday happens early this year. Next year, it will take place on Feb. 12.

Contributing: Kellie Hwang, Indianapolis Star