Why does santa have 7 reindeer on Christmas eve?

Santa traditionally has eight reindeer, as popularized by the poem "A Visit from St. Nicholas" (also known as "The Night Before Christmas"), which names them all, including Rudolph. The idea of Santa having seven reindeer may stem from a misunderstanding or a specific adaptation in some stories. Each reindeer plays a vital role in helping Santa deliver gifts on Christmas Eve, but the iconic image usually includes all eight, with Rudolph often highlighted for his glowing nose.