A work prepared by two or more authors with the intention that each contribution will merge into one inseparable whole. If one songwriter writes all of the music to a joint work and another songwriter writes all of the lyrics to the joint work, each songwriter will own 50% of both the music and lyrics.
The Magic of Song Writing
Like all great musicians, great songwriters are probably born, not made. No tutor, no book, no course, can make you write songs that embed themselves in the memory of a generation.