Giffords was sworn in for her third term Jan. 5.
A conservative blue dog Democrat who previously served as a state legislator and as CEO of her family's automotive tire business.
Her husband of four years, Navy captain Mark Kelly, is an astronaut who is scheduled to command the shuttle Endeavor when it launches in April. His twin brother Scott is currently in command of the international space station and has been informed of the shooting.
The family connections fueled her interest in space. And in Congress she sits on the Science and Technology Committee, as well as Armed Services and Foreign Affairs.
"Whoever did this; whatever their reason, they are a disgrace to Arizona, this country and the human race, and they deserve and will receive the contempt of all decent people and the strongest punishment of the law," said Giffords' fellow Arizonan, Senator John McCain today.
And Democratic Leader Nancy Pelosi called Giffords "a brilliant and courageous member of Congress."
"Gabby is more than just a colleague she is actually a friend," said Arizona Gov. Jan Brewer.
Giffords was one of 20 Democrats whose districts were lit up in crosshairs on a Sarah Palin campaign website last spring. Giffords and many others complained that someone unstable might act on that imagery.
"Palin has crosshairs on our district, people have to realize there are consequences to that," said Giffords on MSNBC.
"My sincere condolences are offered to the family of Rep. Gabrielle Giffords and the other victims of today's tragic shooting in Arizona," read Palin's Facebook status. "On behalf of Todd and my family, we all pray for the victims and their families, and for peace and justice."
On Jan. 6, as dozens of House members read the Constitution on the House floor, it was Giffords who was randomly chosen to read one of the document's most recognizable passages: The First Amendment.
U.S. Capitol police sent an e-mail to members of Congress today warning them to take reasonable and prudent precautions regarding their personal safety and security.
House Speaker John Boehner said, "An attack on one who serves is an attack on all who serves."