¿A qué hora y que día se celebran Nochevieja y Año Nuevo?

Explanation:

Nochevieja is New Year's Eve. Of course, it is celebrated on December 31, all night, every year

Año Nuevo is New Year. Of course, it is celebrated on January 1, every year.

Nochevieja lasts all night. The family meets since about 8:00 p.m. - 10:00 p.m., although the time is not restrictive. The idea is that the family spends the night together waiting for it to be 12:00 pm; listening to music, eating, talking, playing, laughing, having a great time, sharing family traditions. At 12:00 p.m., one by one, all people hug and wish for a happy new year. The party continues after 12:00 pm and people share a big feast after 12:00 p.m.

The next day (just some hours later) is Año Nuevo, January 1st. There is always another meeting during the day, in which people continue celebrating and wishing each other a happy new year.

This is a great party!

Año Nuevo is an official international holiday, celebrated in all Western countries.