It's New Year's Eve, which means there are a bunch of articles out there regarding that most perplexing of traditions, the singing of "Auld Lang Syne." Today I Found Out explains how it became a New Year's Eve staple: In 1929, Guy Lombardo and the Royal Canadian Band performed at a New York hotel on New Year's Eve, with the performance being broadcast on the radio twice. Between broadcasts, they played Scottish folk song "Auld Lang Syne," which Lombardo had learned from Scottish immigrants in Ontario, as a transition between shows—right around midnight.
There were other instances of the song being sung on New Year's Eve, as far back as the mid-19th century, but this is the point at which it started being played at midnight every year on the radio and then TV. So what does the song mean? The title translates literally to "old long since," or figuratively to "times gone by" or "times long past." Dave Tomar attempts to explain its meaning on the Huffington Post: It's "about the endurance of friendship, about cherishing the past even as we look to the future, and quite honestly, about knocking back a few drinks." (Some of the lines: "And surely you'll buy your pint-jug! / And surely I'll buy mine! / And we'll take a cup of kindness yet, / For long, long ago.")