"A Visit from St. Nicholas" (often called "The Night Before Christmas" and "'Twas the Night Before Christmas", from its first line) is a poem, first published anonymously under the title "Account of a Visit from St. Nicholas", in 1823. Authorship has been attributed to Clement Clarke Moore, who claimed authorship in 1837; but it has also been suggested that Henry Livingston Jr. wrote it.
The poem has been called "arguably the best-known verses ever written by an American" and is largely responsible for some of the conceptions of Santa Claus from the mid-19th century to today. It has had a massive effect on the history of Christmas gift-giving. Before the poem gained wide popularity, American ideas had varied considerably about Saint Nicholas and other Christmastide visitors.