Typically it is a star. The star represents the star of Bethlehem, the star the wise men followed to the birth place of Jesus.
A star or angel
Thanksgiving
yes
To put the present under it
Because they want to.
because it is a traditon
Some people have a star or an angel on top of their Christmas tree.
In Australia, many people put up their Christmas tree on the 1st day of December. It varies. There is no tradition in Australia for when to put up the Christmas tree. Some people put it up early in December, while others put it up at various times in the weeks preceding Christmas. Some may leave it until Christmas Eve. There is truly no tradition.
You can put ornaments on a Christmas tree.
lights, ornaments, presents, partridges.
they build a snow tree and put candles on it
19th of july