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.
ðə pɹˈaɪmɚɹi fˈʌŋkʃən ʌvðə ɹˈaʊd fˈoʊk sˈɔŋ ˈɪndɛks ɪz æz ɐ ɹᵻsˈɜːtʃ ˈeɪd kˈɔɹɪlˌeɪɾɪŋ vˈɜːʒənz ʌv tɹɐdˈɪʃənəl ˈɪŋɡlɪʃlˈæŋɡwɪdʒ fˈoʊk sˈɔŋ lˈɪɹɪks ˌɪndᵻpˈɛndəntli dˈɑːkjuːməntᵻd ˌoʊvɚ pˈæst sˈɛntʃɚɹiz baɪ mˈɛni dˈɪfɹənt kəlˈɛktɚz əkɹˌɑːs ɪspˈɛʃəli ðə jˌuːkˈeɪ ænd nˈɔːɹθ ɐmˈɛɹɪkə.