Thousands of couples across China have opted to get married on what is being called "Super Singles Day".
"Singles Day" or "Bachelors Day" is thought to have first been marked in the 1990s by male university students.
They celebrated it on 11 November as the date contains only the number one, which can mean "bare sticks" in Chinese and refer to bachelors.
This year's event is even more significant as it falls on 11/11/11, which happens every 100 years.
Shanghai alone had more than 3,300 couples who booked to get married, but the final tally could be higher as it did not include people who walked in unannounced, a civil affairs bureau spokeswoman told the AFP news agency.
In the eastern city of Nanjing - where most people believe the unofficial festival came from - more than 3,000 couples planned to marry.
This was 10 times the usual daily average, according to the official Xinhua news agency.
One of the more fascinating aspects of any celebration related to a date is the arbitrariness of the calendar itself. The date 11/11/11 refers to the modern Christian calendar, in a world where the majority of people (especially, in this case, China) are not Christian. Go figure.