Korean New Year (Seollal)

Korean New Year, commonly known as Seollal (Hangul: 설날), is the first day of the lunar Korean calendar.
It is the most important of the traditional Korean holidays. It consists of a period of celebrations, starting
on New Year's Day. The Korean New Year holidays lasts three days, and is considered a more important
holiday than the solar New Year's Day.

Korean New Year generally falls on the day of the second new moon after winter solstice, unless there is
a very rare intercalary eleventh or twelfth month in the lead-up to the New Year. In such a case,
the New Year falls on the day of the third new moon after the solstice (next occurrence will be 2033).
Korean New Year is generally the same day as Mongolian New Year, Tibetan New Year, Chinese New Year
and Vietnamese New Year.

Information from Wikipedia.org