Don Emmert, AFP I Hillary Clinton speaks about women’s empowerment on March 10, 2015 at the United Nations in New York

Clinton, the former secretary of state who lost the 2008 presidential nomination, announced her bid in a video message posted on YouTube and on her new . "Everyday Americans need a champion. I want to be that champion," Clinton said as she launched her second run for the presidency. "Americans have fought their way back from tough economic times, but the deck is still stacked in favor of those at the top."

Soon after her announcement, Clinton tweeted that she was heading to Iowa, the first state to vote in next year's primaries. "I'm hitting the trail to earn your vote," she said. The White House hopeful will be looking to connect directly with voters in small, intimate settings – a change in strategy from her last bid, which began with a large, flashy rally in Iowa.

Clinton appears unlikely to face a formidable primary opponent. Should she win the nomination, Clinton would face the winner of a Republican primary field that could feature as many as two dozen candidates, most likely including former Florida Gov. Jeb Bush, the brother and son of former presidents, and Sen. Marco Rubio of Florida, who is expected to announce his campaign in Miami on Monday.

‘Two Clintons for the price of one’

Born in 1947 in Chicago, young Hillary Rodham (later Clinton) was a brilliant student and a Republican, thanks to the influence of her staunchly conservative father and a favourite teacher. She attended prestigious Wellesley University in Massachusetts where she was elected president of the Young Republicans. However, Hillary’s feelings about the Civil Rights movement as well as her opposition to the Vietnam War eventually caused her to migrate to the Democratic Party.

After finishing her undergraduate degree, Hillary attended law school at Yale University in Connecticut. There, she met her future husband Bill Clinton, a student from Arkansas. They married in 1975 and have one daughter, Chelsea.

Bill Clinton went into politics soon after finishing his studies. In 1979, he won the governorship of Arkansas. He lost two years later but won again in 1983, becoming an important figure in the Democratic Party. In 1992, he was elected US president, defeating incumbent George H. W. Bush. Hillary played an active role in the campaign and, at one point, Bill even bragged that the US would be getting “two Clintons for the price of one.”

True to form, after the election, Hillary quickly established herself as a modern and engaged first lady. She accompanied her husband on many state trips and had the opportunity to rub shoulders with many international heads of state.

Bill was easily re-elected in 1996 when he ran against Republican candidate Bob Dole.

Two years into Bill’s second term, a massive scandal shook the Clinton couple and the White House when Bill was forced to admit that he had sexual relations with a young White House intern, Monica Lewinsky. Because Bill had initially lied about the affair under oath, he was accused of unlawful activity and put through an impeachment process, which could have resulted in his removal from office. When Bill was finally acquitted by the House of Representatives, he thanked his wife, who stayed by his side even in the worst moments of the crisis.

A political career of her own

Just before the end of Bill’s second term, Hillary launched her own political career when she decided to run for New York senator. She was on January 3, 2001, during the final days of Bill’s presidency.

During her tenure, Hillary became one of the most visible figures on Capitol Hill, establishing a reputation as a tough, no-nonsense politician. Though she opposed the domestic policies of President George W. Bush, her husband’s successor, she voted in favour of American incursions into Afghanistan and Iraq, choices that could  as she courts the left-wing votes needed to make her the Democratic frontrunner.

In 2006, Hillary was re-elected New York senator with close to 67 percent of the vote. This strong victory positioned her as one of the Democratic favorites for the 2008 presidential primary. However, after several months of campaigning amidst tough competition, Hillary threw in the towel and reluctantly pledged her support for Illinois senator Barack Obama, who would go on to become the nation's first black president.

President Obama named Hillary secretary of state in 2009 and she took the reins of American diplomacy, promising to steer the country in a different direction from the one maintained by the Bush administration. She advocated a strategy of “” a combination of hard and soft power defined by the Center for Strategic and International Studies as "an approach that underscores the necessity of a strong military, but also invests heavily in alliances, partnerships, and institutions of all levels to expand American influence and establish legitimacy of American action."

Hillary visited more countries than any other secretary of state and continued to build her profile on an international scale. The challenges she faced while in office included the Arab Spring and the war in Syria. Her self-described “low point” during her time as top diplomat occurred in September 2012, when the American ambassador to Libya wasalongside three staff members.

‘Politics is a contact sport’

The final months of Hillary’s term as secretary of state were troubled by questions about the Benghazi attacks.

The Senate released a report in early 2014 including findings that the State Department under Clinton had failed to deliver the “standard of care” necessary to protect the embassy staff in Benghazi, concluding that the attack was preventable. However the report found no evidence for the sharpest charges against the Obama administration, including that officials wilfully aired inaccurate information about the attack and delayed a military response.

Hillary stepped down as secretary of state in 2013 and President Obama named John Kerry as her replacement.

Over the past few weeks, Republicans running a select congressional committee reviewing the Benghazi attacks have brought up several new questions. Clinton has faced withering criticism over her use of a personal email account and server while she was the top diplomat and her decision to delete thousands of emails she deemed personal.

She is also dealing with questions over the Clinton Foundation's receipt of donations from foreign governments, such as a $25 million contribution from the Saudi Arabian government.

Despite these lingering concerns, Hillary Clinton has remained the top candidate for the Democratic ticket, even as  if potential rivals like Massachusetts Senator Elizabeth Warren (who has denied the possibility of her own candidacy) will wind up stepping up to the plate.

In an interview with the Associated Press published shortly after she resigned as secretary of state, Hillary said: “You have to have a thick skin because [politics] is just going to be a contact sport as far as we can look into the future."

Having weathered her share of political storms, Clinton looks readier than ever to play ball.