Samuel Langhorne Clemens, better known by his pen name Mark Twain, was an American author and humorist born on November 30, 1835. He is best known for his novels, including The Adventures of Tom Sawyer and Adventures of Huckleberry Finn, which explore themes of childhood, race, and morality in 19th-century America. Twain's writing style is characterized by its wit, social commentary, and use of regional dialects. He was also a prominent public figure, known for his lectures and essays on various social issues. Twain passed away on April 21, 1910, leaving a lasting legacy in American literature.