Philip Alfred Mickelson (born June 16, 1970) is an American professional golfer. He has won four major championships and a total of 39 events on the PGA Tour. He has reached a career high world ranking of 2nd in multiple years. He is nicknamed "Lefty" for his left-handed swing, even though he is otherwise right-handed.

Mickelson was born in San Diego, California, to parents Phil Mickelson Sr. (an airline pilot) and Mary Mickelson. He was raised there and in Scottsdale, Arizona. Although right-handed otherwise, he plays golf left-handed, as he learned by watching his right-handed father swing and mirroring it. Mickelson began golf under his father's instruction before starting school. He graduated from the University of San Diego High School.

Mickelson then attended Arizona State University on a golf scholarship; he graduated in 1992. During his time at Arizona State, he became the face of amateur golf in the United States, capturing three NCAA individual championships and three Haskins Awards (1990, 1991, 1992) as the outstanding collegiate golfer. He was the second collegiate golfer to earn first-team All-American honors all four years. In addition, in 1990, he became the first left-hander to win the U.S. Amateur title. Perhaps his greatest achievement, though, came in 1991 when he won his first PGA Tour event, the Northern Telecom Open. He did so as an amateur, becoming only the sixth player in PGA history to accomplish this feat, and the first since Scott Verplank, who won the 1985 Western Open. In the 20 years since, no one has matched this achievement.