Walt Whitman (1819-1892) was an American poet, essayist, and journalist known for his innovative poetry and celebration of American life. He is often referred to as the father of free verse and is best known for his collection 'Leaves of Grass', a groundbreaking work in American literature. Whitman's writing often focused on nature, the human experience, and democracy, and his work played a significant role in shaping American literary culture.