Also known as Guanggun Jie, this is a Chinese shopping holiday where single men and women are encouraged to treat themselves and celebrate their single status. The date, November 11, was reportedly chosen because the numeral "1" twice represents two singles, or one-one, or single-single. Some call it the "bare sticks holiday" because of how it looks numerically.
The holiday probably began as an anti-Valentine's Day in the 1990s when students at Nanjing University started celebrating their singledom. It was later adopted by e-commerce giant Alibaba which promotes it as a day when everyone, regardless of their single status, buys themselves gifts.