Auld Lang Syne traditionally plays after midnight at New Year's Eve celebrations in many English-speaking countries.
The song is based on a Scots poem published in 1788 and associated with Robert Burns, who helped preserve and shape the text from older Scottish material. Its title means roughly “old long since,” or more naturally, “for old times' sake.” The lyrics ask whether old friendships and memories should be forgotten, then answer with a toast to remembered companions.
The familiar melody became internationally popular during the nineteenth and twentieth centuries. It is especially linked with New Year's Eve, but it is also used at farewells, graduations, funerals, and other moments of transition. Lyrics and verses vary, so many public performances use only the best-known portion.
Auld Lang Syne is not a national anthem, and its New Year's association is cultural rather than a universal legal or religious requirement. Pronunciation and wording can also vary because the song comes from Scots rather than standard modern English.