A songwriter is someone who applies their creative talent to the creation of musical works, writing the music, and sometimes also the lyrics, usually in a popular music style (e.g., rock, country, hip hop, pop). A composer is someone who applies their creative talent to the creation of musical works, composing the music, usually in a classical or jazz musical style. A lyricist is someone who applies their creative talent to the creation of musical works, writing the lyrics, across many styles of music including musical theater.
A shorthand way of referring collectively to songwriters, composers, and lyricists is to refer to them as writers. Writers may be the sole creator of a musical work or may collaborate with other others in its creation. A writer may also be a recording artist.