Are songs, as one dictionary definition suggests, a “mere trifle”? Or do they, in fact, play a highly significant role in human society? This chapter discusses the social functions of songs and singing, drawing on research into the songs folk sing, and why. In particular, it builds on Ernst Klusen’s concept of “group song”, which indicates the special bonds that emerge between social groups and “their” songs. Through continued reuse, groups songs can become one of the ties that hold these groups together. The chapter also introduces the concepts of implied significance and inherited significance to explain how songs can become associated with certain groups, practices, or rituals, including where this is not immediately clear from the basic material of the songs (such as the words or the tune). The chapter closes with a consideration of the particular challenges faced when tracing the complex history of Auld Lang Syne, and introduces further terms and abbreviations used in the book.