In American, Christmas is the biggest holiday of the year, with a deep religious significance for Christians and cultural impact that affects commerce, decorating, the postal service and the "spirit" we're all supposed to feel from Thanksgiving right on through the start of the New Year.

But you may not be familiar with the history of the holiday itself and some of its traditions.

The Birth Of Christ

For centuries, Christians have celebrated the birth of Christ. But they haven't always done so on Dec 25.

Christmas literally means "Christ's mass" or the festival for the anointed one. It is also, as commonly held, a holiday that marks Christ's birth in Bethlehem.

The actual date of Christ's birth, however, has long the topic of discussion, with no consensus in the church until around the fourth century. Early theologians celebrated the occasion on May 20, while others chose late March or April, around the time of the Jewish Passover.

Dec. 25 falls during a time of year when pagans once celebrated winter festivals. It's believed the early church fathers picked the now-familiar date as an alternative to those ancient festivals.

Even now, Russian and Greek Orthodox churches continue to observe the old Julian calendar, celebrating Christmas on Jan. 7.

Christmas Cards

The tradition of sending cards to loved ones (and now business associates) has been around for more than 150 years. The first were designed by British artist J.C. Horsely. They depicted good deeds, and were sent to friends by Sir Henry Cole in 1843.

The cards first came to America in 1875, and have since grown to the point that Hallmark estimates taht 2 billion cards are sent each year for the holidays.

Christmas Carols

The earliest Christmas songs date from Catholic church in the fourth century.

Because they were taken from Latin hymns, they were generally only sung in church.

In medieval times, Christmas music largely followed the Gregorian tradition, and were often sung by minstrels who traveled from castle to castle. The songs that came from Renaissance Italy were lighter and more joyous, but still religious and still in Latin.

Perhaps the most famous of all Christmas carols, "Silent Night," was written in Austria in the early 19th Century.

Since that time, Christmas carols have been written by the popular composers and songwriters of the day, blending the holiday's religious and secular themes.

Santa Claus

Speaking of secular themes... Santa Claus has been a part of the legend of Christmas since the fourth century, but he hasn't always been thought of as a jolly old elf.

The earliest tales of Santa Claus come from what was then Asia Minor, where St. Nicholas was born before moving to Egypt and Palestine as a young man. His practice of giving gifts to needy children made him welcome wherever he visited.

Many years later, the name St. Nicholas became splintered into many variations among the Protestant churches of Europe.

The American image of Santa as a jolly man with white whiskers and an infectious laugh dates back to the 1820s and the poem, "A Visit From St. Nicholas."

Gift Giving

When we give gifts to our loved ones at Christmas, we're continuing a tradition that began when the Three Kings visited the Christ child in Bethlehem. The Three Wise Men brought gifts of gold, frankincense and myrrh to the baby Jesus, as a tribute to the newborn king.

And while the three travelers had great wealth, it's believed that even poor people brought presents to the baby Jesus.

But gift-giving was also a part of many ancient festivals. But since the early Christians didn't want their religion to be associated with pagan festivals, they criticized gift-giving as a pagan ritual. So it didn't become part of the Christmas tradition until several centuries after the birth of Christ, when it finally began to take hold in the Middle Ages.

Other Symbols

Among the items seen every year at Christmas time are the Nativity scene, the candles and the ornaments. They're just some of the many Christmas symbols.

St. Francis of Assisi is credited with beginning the custom of symbolizing Christ's birth in a manger. He celebrated Christmas Mass in front of the early Nativity scene, which included figures of the Virgin Mary, Joseph, the shepherds and their animals.

Candles are often burned around Christmas, symbolizing light and warmth at a time usually associated with the darkness and cold of winter.

In olden days, burning candles were placed on Christmas trees. That practice is now discouraged for safety reasons.

Near the turn of the century an employee of New England Telephone came up with the idea of using electric lights, instead of candles.

The glass and paper ornaments we now place on our Christmas trees stem from the fruits and nuts and flowers that were placed on the first Christmas trees.

And the Advent wreath is a symbol of the coming of Christ. It's traditionally an evergreen wreath with four candles, which are lit on each of the four Sundays before Christmas.