"You'll Never Walk Alone" is a show tune from the 1945 Rodgers and Hammerstein musical Carousel. In the second act of the musical, Nettie Fowler, the cousin of the female protagonist Julie Jordan, sings "You'll Never Walk Alone" to comfort and encourage Julie when her husband, Billy Bigelow, the male lead, commits suicide after a failed robbery attempt. It is reprised in the final scene to encourage a graduation class of which Louise (Billy and Julie's daughter) is a member. The now invisible Billy, who has been granted the chance to return to Earth for one day in order to redeem himself, watches the ceremony and is able to silently motivate the unhappy Louise to join in the song.

The song was adopted by Scottish soccer team Celtic after a 1966 Cup Winners Cup semi-final against Liverpool. It is now sung by Celtic fans prior to every home European tie. The song has also been adopted by many soccer teams all over the world.

More Info: en.wikipedia.org