The Roud Folk Song Index is a database of around 250,000 references to nearly 25,000 songs collected from oral tradition in the English language from all over the world. It is compiled by Steve Roud (born 1949), a former librarian in the London Borough of Croydon. Roud's Index is a combination of the Broadside Index (printed sources before 1900) and a "field-recording index" compiled by Roud. It subsumes all the previous printed sources known to Francis James Child (the Child Ballads) and includes recordings from 1900 to 1975. Until early 2006, the index was available by a CD subscription; now it can be found online on the Vaughan Williams Memorial Library website, maintained by the English Folk Dance and Song Society (EFDSS). A partial list is also available at List of folk songs by Roud number. Purpose of index The primary function of the Roud Folk Song Index is as a research aid correlating versions of traditional English-language folk song lyrics independently documented over past centuries by many different collectors across (especially) the UK and North America. It is possible by searching the database, for example by title, by first line(s), or subject matter (or a combination of any of a dozen fields) to locate each of the often numerous variants of a particular song. Comprehensive details of those songs are then available, including details of the original collected source, and a reference to where to find the text (and possibly music) of the song within a published volume in the EFDSS archive. A related index, the Roud Broadside Index, includes references to songs which appeared on broadsides and other cheap print publications, up to about 1920. In addition, there are many entries for music hall songs, pre-World War II radio performers' song folios, sheet music, etc. The index may be searched by title, first line etc. and the result includes details of the original imprint and where a copy may be located. The Roud number – "Roud num" – field may be used as a cross-reference to the Roud Folk Song Index itself in order to establish the traditional origin of the work. The database is recognised as a "significant index" by the EFDSS and was one of the first items to be published on its web site after the launch of the online version of the Vaughan Williams Memorial Library in 2006. Numbering scheme and cross references The