what is the best selling christmas song

The most popular Christmas song is "Silent Night," written by Franz Gruber and Josef Mohr in 1818. The song has been translated into over 300 languages and dialects, making it the most translated Christmas carol in the world. It is known for its simple and beautiful melody, which has been covered by many famous singers and musicians over the years. It's also considered a staple of Christmas music and is often played during the holiday season.