The United States ten-dollar bill ($10) is a denomination of United States currency. U.S. Secretary of the Treasury Alexander Hamilton is currently featured on the obverse of the bill, while the U.S. Treasury is featured on the reverse. (Hamilton is one of two non-presidents featured on currently issued U.S. bills. The other is Benjamin Franklin, on the $100 bill.) All $10 bills issued today are Federal Reserve Notes.
The Bureau of Engraving and Printing says the "average life" of a $10 bill in circulation is 18 months before it is replaced due to wear. Approximately 11% of all newly printed US banknotes are $10 bills. Ten dollar bills are delivered by Federal Reserve Banks in yellow straps.
The source of the face on the $10 bill is John Trumbull's 1805 portrait of Hamilton that belongs to the portrait collection of New York City Hall. The $10 bill is the only U.S. paper currency in circulation in which the portrait faces to the left (the $100,000 bill features a portrait of Woodrow Wilson facing to the left, but it is no longer in circulation).

Small size note history
The $10 bill has several nicknames, including:

Sawbuck, based on the resemblance of the Roman numeral "X" on some of the earlier designs to the carpentry device of the same name. This usage is far less common today than it was in the early 20th century.
Hamilton, Alex, Al or Alexander based on the use of Alexander Hamilton's portrait
Tenner, borrowed from British reference to the 10-pound note, is rarely used in the US but generally understood.
Ten Spot