She married her husband, Denis Thatcher, a local businessman who ran his family's firm before becoming an executive in the oil industry, in 1951 -- a year after an unsuccessful run for Parliament. The couple had twins, Mark and Carol, in 1953.
She was elected to Parliament in 1959 and served in various positions, including education secretary, until her terms as prime minister.
Thatcher was awarded the U.S. Medal of Freedom by President George H. W. Bush in 1991, a year after she stepped down as prime minister. She was named Baroness Thatcher of Kesteven after leaving office.
She retired from public life after a stroke in 2002 and suffered several smaller strokes after that. Her husband died in June 2003.
Though her doctors advised against public speaking, a frail Thatcher attended Reagan's 2004 funeral, saying in a prerecorded video that Reagan was "a great president, a great American, and a great man."
"And I have lost a dear friend," she said.
In the years that followed she encountered additional turmoil. In 2004, her son Mark was arrested in an investigation of an alleged plot by mercenaries to overthrow the president of Equatorial Guinea in west Africa. He pleaded guilty in a South African court in 2005 to unwittingly bankrolling the plot.