Spain is the country especially associated with the New Year's Eve tradition of eating 12 grapes at midnight.
The custom is known as las doce uvas de la suerte, or “the twelve grapes of luck.” Participants try to eat one grape with each stroke of the clock at midnight on December 31. The twelve grapes represent the twelve months of the coming year, and successfully eating them is said to bring good fortune.
Madrid's Puerta del Sol is a famous public setting for the ritual. The clock there is broadcast nationally, and people across Spain follow its midnight chimes. Families and public gatherings often prepare the grapes in advance because the pace can be surprisingly fast.
The tradition is sometimes explained as a response to a surplus grape harvest in the early twentieth century, though earlier elite examples have also been documented. It is a Spanish custom, even though grape-based New Year practices exist elsewhere.