In the U.S. many people in the United States celebrate Christmas Day on December 25. The day celebrates Jesus Christ’s birth. It is often combined with customs from pre-christian winter celebrations. Many people erect Christmas trees, decorate their homes, visit family or friends and exchange gifts. People/Families who are not christian’s sometimes just visit their family just to see them, and they open presents just to open them and get stuff. But most are christian’s. 
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In Japan Christmas in known as more of a time to spread happiness rather than a religious celebration.Christmas Eve is often celebrated more than Christmas Day. Christmas eve is thought of as a romantic day, in which couples spend together and exchange presents. Fried chicken is often eaten on Christmas day. 
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In Germany Christmas Eve is celebrated on December 24. It is the last day of Advent and the start of the Christmas season. Many people spend the afternoon and evening decorating Christmas trees, attending church services, eating traditional dishes and opening Christmas presents. 
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My information –
I got some of the us information from timeanddate.
I also got some of the Japan information from whychristmas.
Finally, I got my some of the Germany information from timeanddate.