Final answer:
Walt Whitman, born in 1819, was a notable American poet who authored 'Leaves of Grass' and popularized free verse. His works celebrate common life and language, and he remains a significant figure in American literature.
Step-by-step explanation:
Born in rural New York in 1819, Walt Whitman evolved from a teacher and journalist to become a central figure in American poetry. His seminal work, Leaves of Grass, introduced the world to free verse and contained poems such as "O Captain! My Captain!", an ode to Abraham Lincoln, "I Sing the Body Electric", "Song of Myself", "When I Heard the Learn'd Astronomer", and "Crossing Brooklyn Ferry". His work is characterized by its celebration of the common people and the common language, and he is known for embracing topics that ranged from the everyday life to national mourning and celebration.
During the Civil War, Whitman also contributed to the war effort by caring for wounded soldiers. He passed away in 1892, leaving behind a powerful legacy that continued to shape American literature. His influence extends beyond his time as he encapsulates the transcendentalist movement and addresses the rapid modernization of the nation through his poetry, making him one of the most revered figures in American literature.