(CNN)Here's a look at Christmas, a popular Christian holiday celebrating the birth of Jesus Christ.
Celebrated December 25th in the United States and other countries. In 2021, December 25th falls on a Saturday.
Christmas is celebrated on January 7 in some Eastern Orthodox countries, such as Russia.
The real date of Jesus' birth is not known.
The Christmas story is told primarily in the Gospels of Saint Luke and Saint Matthew in the New Testament.
Considered the most popular Christian observance, Christmas is also celebrated as a secular family holiday.
The word Christmas is derived from the Old English phrase Cristes maesse (Christ's mass).
The tradition of substituting X-mas for Christmas has its origins in the early Christian church. The first letter of Jesus Christ's name is X in the Greek language.
Many of the customs and symbols traditionally associated with Christmas originated with ancient pagan festivals and winter solstice rituals.
The modern Christmas tree (typically evergreen conifers-usually pine, balsam or fir species) originated in Germany in the 16th century and became popular in England by the mid-19th century thanks to Queen Victoria's husband, Prince Albert, who was German.
St. Nicholas, the real person on whom Santa Claus is based, lived in the 4th century AD in the province of Lycia on the southwest coast of Asia Minor.
Cartoonist Thomas Nast is credited with creating the current image of Santa Claus, based on his illustrations that began appearing in Harper's Weekly in 1863.
The National Retail Federation projects 2021 holiday sales between $843.4 billion and $859 billion, an increase of 8.5% to 10.5% over 2020 spending.
The United States Post Office anticipates delivering 850 million and 950 million packages during the 2021 holiday season.