Singles Day: 4 things to know about the world's biggest shopping promo

China's wackiest mall attractions

In less than a decade, Chinese internet giant Alibaba has transformed Singles Day into a capitalist extravaganza during which consumers are expected to spend $23 billion this year on gifts for themselves and others.

Here's a closer look at the world's largest online shopping holiday.

What is Singles Day?

It's a 24-hour "festival" that starts Friday. Consumers can find deals on 15 million products from 140,000 brands. Other shopping "holidays" pale in comparison. According to eMarketer, online spending in the US on Black Friday totaled $2.74 billion last year. Amazon reportedly generated $3 billion in sales during Amazon Prime Day earlier this year.

How did it start?

The holiday originated in China's Nanjing University in the 1990s when four friends were lamenting the loneliness and monotony of single life. Someone -- it isn't clear who -- then came up with the idea of celebrating single people on Nov. 11. The day was chosen because it takes four ones to write out the date, 11/11. At first, Singles Day was mainly celebrated by men but now both sexes partake in the festivities. Alibaba organized the first Singles Day sale in 2009.

"We looked at Black Friday in the US and said, 'why don't we have our own Black Friday in China?'" said Alibaba CEO Daniel Zhang in a statement on its website. "November is a good time of year for a sale, but there are no good Chinese festivals in November. So we found a little-known day, on November 11th known as 'Single's Day.'"

How is it changing?

Faced with waning interest in the holiday, Alibaba began this year's Singles Day promotion in October and is now trying to rebrand the celebration as the "11.11 Global Shopping Festival."

"The inclusion of the word "global" is particularly interesting because Alibaba has made no secret of the fact that it hopes to entice shoppers in Europe -- and even the US -- to click and take advantage of sales deals," according to eMarketer.

What companies are involved?

Among the US companies scheduled to participate in this year's Singles Day are consumer electronics firm Bose, toymaker Mattel (MAT), snack foods provider Mondelez (MDLZ), athletic apparel firm Nike (NKE) and consumer products giant Procter & Gamble (PG).