Mark Twain was born in Florida, Missouri. He was first a printer (1847-55), and later a Mississippi river-boat pilot (1857-61). In his first writing he adopted his pen-name from a well-known call of the man sounding the river in shallow places ('mark twain' meaning 'by the mark two fathoms').
In 1861 he went to Carson City, Nevada, as secretary to his brother, who was in the service of the governor, and while there made an unsuccessful attempt at gold mining. For two years he edited the Virginia City Territorial Enterprise and in 1864 moved to San Francisco as a reporter. His first success was The Celebrated Jumping Frog of Calaveras County (1865), which was published as a book with other sketches in 1867. In 1867 he visited France, Italy and Palestine, gathering material for his Innocents Abroad (1869), which established his reputation as a humourist. After his return he was for a time editor of a newspaper in Buffalo, where he married the wealthy Olivia Landon.
Later he moved to Hartford, Connecticut, and joined a publishing firm which failed, but largely recouped his losses by lecturing and writing. Roughing It (1872) is a humorous account of his Nevada experiences, while The Gilded Age (1873), written with Charles Dudley Warner, a novel which was later dramatized, exposes the readjustment period after the Civil War. He visited England for a lecture tour in 1872, and as a result wrote The Prince and the Pauper (1882) and A Connecticut Yankee in King Arthur's Court (1889).
His two greatest masterpieces, Tom Sawyer (1876) and Huckleberry Finn (1884), are drawn from his own boyhood experiences, and give vivid accounts of life on the Mississippi frontier; other Twain favourites include A Tramp Abroad (1880). In 1883 he published Life on the Mississippi, an autobiographical account of his days as a river-boat pilot, which includes a famous attack on the influence of Walter Scott.
From the 1890s to the end of his life, Twain was affected by financial problems, which were aggravated by his unsuccessful business ventures. He tried to recover his fortunes by undertaking lecture tours in New Zealand, Australia, India and South Africa; but his difficulties intensified with the death of his wife (1904) and two of his daughters. His writing from these years has a more sombre tone, notably in The Man that Corrupted Hadleyburg (1900) and The Mysterious Stranger (published posthumously in 1916).
In these last years he dictated his autobiography to his secretary A B Paine, and it was published in different versions.