Kiribati moved west of the International Date Line in 1995, changing when its eastern islands celebrated New Year's Eve.
Kiribati is spread across a huge area of the central Pacific Ocean, including islands that were previously divided by the date line. The government shifted the line around the country's territory so the islands could share the same calendar date and conduct national administration more easily.
The change meant that the Line Islands, including Kiritimati, or Christmas Island, became among the first inhabited places to enter a new calendar day. This made Kiribati especially prominent in discussions of which places welcome a new year first.
The date line is not a perfectly straight natural boundary. It is an agreed convention that bends around countries and territories. Kiribati's 1995 adjustment is therefore a political and practical calendar change, not a movement of the Earth or a change in the length of a day.