Walt Whitman's poetry is characterized by its themes of individualism, democracy, and the connectedness of all humanity. His work celebrates the American experience through free verse and a candid exploration of sexuality and nature. Whitman employs imagery and personification, emphasizing self-expression and the democratic spirit, particularly in "Leaves of Grass." His inclusive voice aims to bridge social and cultural divides, making his poetry a cornerstone of transcendentalism and a precursor to modernist themes.