The flag of the United States is a symbol. A symbol is a word, an idea, or an object that represents something else. Other symbols of the United States are the bald eagle, the Statue of Liberty and Uncle Sam. Nations began to represent themselves with flags so that sailors at sea and soldiers in the field could indentify their own ships and troops. Over time, many Americans have come to associate the flag with powerful emotions and important values, such as patriotism, loyalty and duty.
The elements of a flag's design are called charges. Charges on the U.S. flag comprise a blue canton (flag-speak for a quarter), white stars symbolizing heavenly guidance, and red and white stripes representing purity and valor.
Ben's Guide to U.S. Government
The design of the U.S. flag and regulations for its care and display are codified in federal law.
U.S. Code, TITLE 4--CHAPTER 1--THE FLAG
Legend has it that Betsy Ross sewed the first American flag. No one knows the true story, but Betsy Ross was paid a substantial sum by the Continental Navy in 1777 for sewing flags. This means that she was, in fact, making flags as soon as there were flags to make.
Betsy Ross homepage (Independence Hall Association)
Betsy Ross House
Between the original design of thirteen stars and the fifty-star flag of today, there have been 28 versions of the U.S. flag. You can learn about each of them here.
Flags of the World: The worlds largest vexillogical (that means having to do with flags) database
Th U.S. flag ,in its fifteen-star, fifteen-stripe version, also inspired our national anthem, "The Star-Spangled Banner."
The Star Spangled Banner at the Smithsonian Institution
The actual flag that flew over Ft. McHenry was sewn by a Marylander, Mary Pickersgill.
Mary Pickersgill article at the Maryland Online Encyclopedia
When Alaska and Hawaii became the 49th aand 50th states in 1959, the new 50-star flag made its first appearance at Ft. McHenry.
50-star flag debuts in Baltimore
Flag desecration laws were originally intended to prevent the use of the flag in advertising. This and other fun flag facts can be found at author Marc Leepson's webpage.
Some fun flag facts
The Biggest (and Best) Flag That Ever Flew, by Rebecca Jones (1988).
Stars and Stripes: The Story of the American Flag, by Sarah L.Thompson (2003).
The Story of the Star Spangled Banner, by Lori Damando (2009).
American Flags: Designs for a New Nation, by Nancy Druckman (2003).
Flag: An American Biography, by Mark Leepson (2005).