It almost seems silly to talk about who Mark Twain is. Everyone knows Mark Twain.
On the other hand, "everyone" has read Huckleberry Finn also. OK, raise your hand if you've actually read Huck Finn before, not just seen some movie version... (Pause... counting...) Um hmmm - that's about one in ten.
Mark Twain was born Samuel Langhorne Clemens. (Love the middle name!)
He was born in Florida, Missouri, in 1835. OK, you're all saying "WRONG! - He's from Hannibal!". Yes, he was reared in Hannibal, but he was born in Florida. (Twain says the population in Florida was 100 when he was born. In 2007, the population of Florida was 8. Not 800, 8.) The Clemens family moved to Hannibal in 1839.
Twain's dad was a shopkeeper who apparently had little business sense. Dad passed away when Twain was 12. Twain had to leave school at 12 and get a job learning typesetting at the local newspaper.
That lead to Twain's life-long affiliation with various newspapers and writing.
When Twain was about 17, he started working for his brother, Orion Clemens, who owned several newspapers. Orion and Twain apparently inherited their business sense from their father, and the papers were less than successful. Twain left for about three years, and then came back and worked for Orion again, at the local newspaper.
When Twain was about 22, he left and decided to travel down the Mississippi. He ended up as an apprentice on a Mississippi steamboat. Two years later he got his own pilot's license. This was 1859, so we're talking about a ship's pilot here!
The Civil War happened next. The war pretty much shut down the Mississippi River, as the Union Army used the river heavily, and it generally wasn't a safe place to be. Twain joined the Confederate Army for a bit, then went west to join Orion.
Orion had been given the cushy job as Secretary for the Territory of Nevada. Twain worked for Orion for a couple of weeks, but the draw of the Comstock Lode under Virginia City was too tempting. Like most would-be miners, Twain didn't make it in the goldfields, but he was able to get a job working for the Territorial Enterprise, Virginia City's newspaper.
One thing lead to another, and Twain left Virginia City in 1864, before Nevada became a state. He returned only twice, on speaking tours - once in 1866, and again in 1868. He never returned after that.
For as short a time as Twain spent in Nevada, he has added a lot to the local legends. He's featured often in Nevada's Historical Myth a Month, written by the amazing historian (and former Nevada Archivist) Guy Rocha. Twain is featured in Myth 2 (Mark Twain Flees Nevada!), Myth 37 (Quoting Mark Twain), Myth 54 ("Sell the Sizzle, and not the Steak", Mark Twain in Carson City), Myth 69 (Mark My Words - No Twain in Church), Myth 89 (Never the Twain shall Meet), Myth 101 (In Search of an Enterprising Mark Twain), and Myth 122 (What Mark Twain Didn't Say). Twain shows up in many more of the myths. He was a busy fellow.
After leaving Nevada, Twain did this and that. He got married in 1870. He and his family lived in Connecticutt for about 20 years. He published Tom Sawyer in 1875. He published Huck Finn in 1885.
His entire family died before he did, and he passed away in 1910, a notable curmudgeon.
In Myth 37, Guy Rocha said (I'm going to have to paraphrase this), if it was funny and folksy and a bit cynical, everyone thinks that Mark Twain must have said it. And if it wasn't Mark Twain, it was probably either Will Rogers or Yogi Berra.
That's how much Mark Twain has become a part of our national heritage.