Ariel was the second book of Sylvia Plath's poetry to be published, and was originally published in 1965, two years after her death by suicide.

Plath's work in Ariel is intensely personal. The darkly lyric poems address motherhood, sexuality, marriage, and her own experiences with depression. Despite the positive critical reception of her first, more traditional book, Colossus, the poems in Ariel were initially refused by many of the best editors in the country—the New Yorker would not publish more than a few lines of her later work.

Her late poetry, collected in Ariel, includes some of the best-known contemporary poems in the English language, including "Daddy," "Lady Lazarus," "Ariel," and the opening poem of the collection: "Morning Song".