Original: Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), better known by the pen name Mark Twain, was an American author and humorist.
Simplified: Mark Twain is the pen name of Samuel Langhorne Clemens (November 30, 1835 - April 21, 1910), a well known and well liked American writer born in Florida, Missouri.