Christmas

Christmas is an important festival for Christian. According to Bible, Jesus Christ was born in a manger, in Bethlehem. However, the date couldn’t be traced back, so Christian changed Rome Empire’s anniversary as Christmas.
To talk about Christmas, the first thing I think is the Santa Claus. Legend has it that Santa Claus will send gifts to children at Christmas Eve, and it becomes a tradition that children will expect the coming of this day. Though I know the truth after I grow up, those gifts are prepared by parents; I still had a wonderful time and I indeed cherished the memory. To receive gifts form Santa is children’s dream, and this day is also a reunion for lots of family.
Christmas Day is celebrated as a major festival and public holiday in most countries of the world, even in many whose populations are not majority Christian. In some non-Christian countries, periods of former colonial rule introduced the celebration (e.g. Hong Kong); in others, Christian minorities or foreign cultural influences have led populations to observe the holiday. Major exceptions, where Christmas is not a formal public holiday, include People's Republic of China, (except Hong Kong and Macao), Japan, Saudi Arabia, Algeria, Thailand, Nepal, Iran, Turkey and North Korea.
Around the world, Christmas celebrations can vary markedly in form, reflecting differing cultural and national traditions. Countries such as Japan and Korea, where Christmas is popular despite there being only a small number of Christians, have adopted many of the secular aspects of Christmas, such as giftgiving, decorations and Christmas trees.

The modern Mother's Day is celebrated on various days in many parts of the world, most commonly in May or in March/April, as a day to honor mothers and motherhood. In the UK and Ireland, it follows the old traditions of Mothering Sunday, celebrated in March/April.
As the US holiday was adopted by other countries and cultures, the date was changed to fit already existing celebrations honoring motherhood, like Mothering Sunday in the UK or the Orthodox celebration of Jesus in the temple in Greece. In some countries it was changed to dates that were significant to the majority religion, like the Virgin Mary day in Catholic countries, or the birthday of the daughter of the Prophet Muhammad in Islamic countries. Other countries changed it to historical dates, like Bolivia using the date of a certain battle where women participated.

Halloween

Halloween (also spelled Hallowe'en) is an annual holiday observed on October 31. It has roots in the Celtic festival of Samhain and the Christian holiday All Saints' Day, but is today largely a secular celebration.
Halloween activities include trick-or-treating, wearing costumes and attending costume parties, carving jack-o'-lanterns, ghost tours, bonfires, apple bobbing, visiting haunted attractions, pranks, telling scary stories, and watching horror films.

Trick-or-treating is a customary celebration for children on Halloween. Children go in costume from house to house, asking for treats such as candy or sometimes money, with the question, "Trick or treat?" The word "trick" refers to a (mostly idle) "threat" to perform mischief on the homeowners or their property if no treat is given. In some parts of Scotland children still go guising. In this custom the child performs some sort of trick, i.e. sings a song or tells a ghost story, to earn their treats.

Valentine's Day

Valentine’s Day is the traditional festival in western countries, and people celebrate it on February 14th. It is the date to commemorate a Christian named Valentine at first. After several centuries, this festival becomes well-known and people combine it with the story of Cupid. While sending cards, flowers, chocolates and other gifts is traditional in the UK, Valentine's Day has various regional customs. In Spain Valentine's Day is known as "San Valentín" and is celebrated the same way as in the UK, although in Catalonia it is largely superseded by similar festivities of rose and/or book giving on La Diada de Sant Jordi (Saint George's Day).
In addition, in Asia, we have another Valentine’s Day. It is at July 7th , the lunar calendar, and it has a beautiful Chinese myth. Nowadays, we celebrate both Chinese and Western Valentine’s Day.