Leaves of Grass is a poetry collection by American poet Walt Whitman. After self-publishing it in 1855, he spent most of his professional life writing, revising, and expanding the collection until his death in 1892. Either six or nine separate editions of the book were produced, depending on how one defines a new edition. The continual modifications to Leaves of Grass resulted in vastly different copies of it circulating in Whitman's lifetime. The first edition was a slim tract of twelve poems, and the last was a compilation of over 400 poems.
The book represents a celebration of Whitman's philosophy of life and humanity in which he praises nature and the individual's role in it. He catalogues the expansiveness of American democracy. Rather than dwell on religious or spiritual themes, he focuses primarily on the body and the material world. With very few exceptions, Whitman's poems do not rhyme or follow conventional rules for meter and line length.