A Blue Dog Democrat and fiscal conservative, Giffords has taken a tough line on immigration reform -- her district shares a 100-mile border with Mexico -- and in support of gun rights.
Her more controversial recent votes in Congress include supporting President Obama's stimulus plan and health care reform -- the latter for which she received threats reportedly from opponents of the law.
But "Gabby," as she is known to staff, friends, constituents and colleagues, is no heat-seeking firebrand. A well-regarded centrist, Giffords, 40, plays the French horn, rides motorcycles and is widely considered a politician going places.
"Gabby is very sweet, very nice. She's tough. She's smart," Houston restaurateur Tilman Fertitta, a family friend, told ABC News. "I've always said Gabby is gonna go a long way."
Fertitta attended Giffords' 2007 wedding to Navy captain and astronaut Mark Kelly. He said it was Kelly who called him with the news that Giffords had been shot.
"Mark's a pretty cool cookie," Fertitta said. "But this was definitely a pretty frazzled guy, because you're not there."
Kelly, who flew to Arizona from Texas to be with his wife shortly after she was injured, is scheduled to command the 134th NASA shuttle flight Endeavour on April 1. His twin brother, Scott Kelley, is commander of the International Space Station, and the two were to rendezvous in space.
Giffords remained in critical condition Sunday following a mass shooting at a neighborhood event in her district that left six dead and 14 wounded. Shot through the head, Giffords was in a medically induced coma, according to surgeons.
Suspected shooter Jared Lee Loughner, 22, was in federal custody and authorities were seeking a possible accomplice. Police said Giffords was the target.
"This was an attack not only against dedicated public servants, but against our citizens," said FBI Director Robert Mueller, who was sent to Arizona by Obama to oversee the investigation.
Giffords, in a March 2010 television appearance, lamented the heated political rhetoric in the nation and also in her mostly Republican district, and worried about the "consequences" of vitriolic speech in politics.
Born in Tuscon, Giffords graduated from Scripps College and Cornell University, before taking over the family tire and auto business, El Campo Tire Inc. The company was later sold to Goodyear.
During her undergraduate days, Giffords won a prestigious William Fulbright Scholarship and spent a year studying in Mexico.
Elected to the Arizona state house in 2001, Giffords served until 2005, when she was elected to the state senate. In 2006, she ran for Congress and joined a Democratic House class that took over the majority from Republicans.
In Congress, Giffords serves on the House Armed Services Committee and is active on issues related to NASA and space. Her signature issues include solar energy, the military and border.