"Rehab" by Amy Winehouse is a soul and R&B song written by the British singer herself. It was recorded for her second studio album, "Back to Black," released in 2006. The song was written as a reflection of Winehouse's personal struggles with addiction and her resistance to seeking help. "Rehab" became one of her most successful and recognizable tracks, reaching high positions on charts globally. The composition is in the key of C major, and it showcases Winehouse's unique vocal style characterized by its deep, soulful timbre. The melody combines elements of jazz, Motown, and vintage R&B, giving the song a timeless and nostalgic feel.