Everything you need to know about Christmas, and how it has evolved into a global holiday

Christmas is a Christian holiday that observes the birth of Jesus.

- BY LUIS ANDRES HENAO

But did you know that the earliest followers of Jesus did not annually commemorate his birth? Or that Santa Claus is inspired by the acts of kindness of a fourth-century Christian saint?Since the early 20th century, Christmas has evolved from a religious holiday to a hugely popular cultural holiday observed by Christian and secular people across the globe who gather with families, exchange gifts and cards and decorate Christmas trees.

Here's a look at the history, beliefs and the evolution of Christmas:

Origins and early history of Christmas

Early followers of Jesus did not annually commemorate his birth but instead focused on commemorating their belief in his resurrection at Easter.

The story of the birth of Jesus appears only in two of the four Gospels of the New Testament: Matthew and Luke. They provide different details, though both say Jesus was born in Bethlehem.

The exact day, month and even year of Jesus's birth are unknown, said Christine Shepardson, a professor at the University of Tennessee who studies early Christianity.

The tradition of celebrating Jesus' birth on Dec. 25, she said, only emerged in the fourth century.