As ABCNews.com marks 25 years, a look back at the biggest stories we covered

When ABCNews.com launched on May 15, 1997, Bill Clinton was president and the nation was months away from learning of his sex scandal with White House intern Monica Lewinsky.

The iPhone was still a decade from being introduced by Apple and the space shuttle Atlantis was blasting off on its 19th flight.

The mission for the site then, as it is now, was to provide ABC News' legion of viewers and radio listeners a 24/7 news platform on what was then commonly referred to as the World Wide Web.

Since then, ABCNews.com has covered politics, terrorist attacks, mass shootings, wars and climate change.

The 25-year-old website has become one of the largest around-the-clock online news platforms in the nation with audiences consuming multimedia stories from around the globe, including videos, blogs, podcasts and most recently, ABC News' Live streaming newscasts.

Here are some of the top stories from the past quarter century that ABC News Digital has covered:

1997 -- Princess Diana's death

On Aug. 31, 1997, the Princess of Wales, and her companion, Dodi Fayed, were killed in a crash in Paris when their driver lost control of a Mercedes-Benz while trying to outrun a pack of paparazzi. The heartbreaking story, and its intricacies have captivated the world in the years since.

1998 -- President Bill Clinton's impeachment

On Dec. 19, 1998, the 42nd president of the United States was impeached on grounds of committing perjury before a grand jury and obstruction of justice stemming from a sexual harassment lawsuit filed by Paula Jones. The case publicly exposed Clinton's affair with White House intern Monica Lewinsky. Clinton emerged from the impeachment proceedings with a 71% approval rating and the Senate ultimately acquitted him of the charges, allowing him to serve out the rest of his second term.

1999 -- Columbine High School massacre

One of the deadliest school shootings in U.S. history took place on April 20, 1999, when two teenagers launched an attack at their school -- Columbine High in Littleton, Colorado -- killing 12 students and a teacher and wounding more than 20 people. The two gunmen, Eric Harris, 18, and Dylan Klebold, 17, died by suicide.

2000 -- Presidential election decided by the Supreme Court

In December 2000, Republican Texas Gov. George W. Bush was declared the winner of a disputed presidential election over incumbent Vice President Al Gore. The election prompted a hotly contested recount of the vote in Florida, numerous legal challenges and was ultimately decided in a narrow 5-4 U.S. Supreme Court decision.

2001 -- Sept. 11th attacks

Hijackers belonging to the international terrorist network al-Qaeda hijacked four commercial planes, crashing two into New York City's World Trade Center and one into the Pentagon in Arlington, Virginia. The fourth hijacked plane crashed into a Pennsylvania field after passengers confronted the hijackers, thwarting another attack. Nearly 3,000 people died in the attacks, making them the deadliest terrorist strikes on U.S. soil. The attacks triggered the war in Afghanistan, an al-Qaeda safe haven, and a hunt for terrorist mastermind Osama bin Laden.

2002 -- Catholic church sex abuse exposed

In January 2002, the Boston Globe published an article that revealed that the Catholic Archdiocese of Boston had moved a priest defrocked in 1998 from one parish to another, even though records indicated church officials knew of his pedophilia for more than 20 years. By the middle of February, the archdiocese disclosed the names of 87 other priests who had also been accused of sexually abusing children. A series of revelations followed about how the Roman Catholic church mishandled cases of sexual abuse of minors by priests, causing public outrage and sparking reform efforts.

2003 -- Iraq War

In March 2003, the United States led an international coalition in an invasion of Iraq, which the U.S. officials claimed was developing weapons of mass destruction. Following an air assault on targets in the Iraqi capital, Baghdad, the U.S.-led coalition launched a ground war that led to the seizure of Baghdad and the ouster of the country's dictator, Saddam Hussein. Combat operations ended 18 years later.

2004 -- Indonesia earthquake and tsunami

A massive underwater earthquake near the Indonesian island of Sumatra spawned a tsunami that killed some 230,000 people and displaced an estimated 1.6 million others in more than a dozen countries from Indonesia to Kenya. The tsunami caused unprecedented destruction in many coastal areas of the Indian Ocean.

2005 -- Hurricane Katrina

Hurricane Katrina was one of the worst natural disasters ever to strike the U.S. It was originally designated a Category 4 storm—though later analysis said it was likely a Category 3 storm—with winds of 145 mph when it first struck Louisiana on Aug. 29, 2005, leading to the flooding of New Orleans and massive damage along the coasts of Mississippi and Alabama. In August 2006, the National Hurricane Center reported at least 1,833 deaths directly or indirectly caused by Katrina, including 1,577 in Louisiana.

2006 -- US housing begins long slide to collapse

The sizzling hot U.S. housing market started to collapse under the weight of subprime mortgages being approved for high-risk borrowers, many with poor credit. The Federal Reserve raised the federal funds rate, sending adjustable mortgage interest rates soaring. Housing prices dramatically plummeted as a result and borrowers defaulted in record number.

2007 -- Global economic downturn

A major U.S. and global economic downturn began in 2007 and intensified in September 2008 as the housing market continued to collapse and stock markets suffered the largest losses since the Great Depression. Some financial institutions were left holding trillions of dollars in nearly worthless subprime mortgages, including global investment companies like Bear Stearns, which saw two of its hedge funds go belly up.

2008 -- 1st US Black president elected

In the historic Nov. 4 election, Sen. Barack Obama, D-Illinois, and his running mate, Joe Biden, beat Arizona Republican Sen. John McCain and then-Alaska Gov. Sarah Palin by a wide margin in the Electoral College. The Obama-Biden ticket also won a majority of the popular vote, becoming the first Democratic ticket to do so since 1976. Obama, whose Black father was from Kenya and whose white mother was from Kansas, became the country's first Black president, inheriting a nation in deep financial crisis.

2009 -- Swine flu emergency

The H1N1 swine influenza virus first emerged in spring 2009 in North America and quickly spread worldwide. On June 11, 2009, the World Health Organization (WHO) declared a pandemic, raising its alert system to the highest level, Phase 6, for the first time since 1968. Hundreds of thousands of people were estimated to have died worldwide during the virus's initial year of circulation, while millions of infected people were thought to have suffered only mild symptoms before recovering fully.

2010 -- Massive earthquake hits Haiti

On Jan. 12, 2010, a magnitude 7.0 earthquake struck Haiti's capital, Port-au-Prince, killing some 220,000 people, according to the U.N., and leaving at least 1 million more homeless.

2011 -- Osama bin Laden killed

The decade-long search to bring Osama bin Laden to justice ended when the U.S. Navy's special forces unit SEAL Team 6 raided the terrorist leader's safe house in Abbottabad, Pakistan, on May 2, 2011, killing him. "Tonight, I can report to the American people and to the world that the United States has conducted an operation that killed Osama bin Laden, the leader of al-Qaeda, and a terrorist who’s responsible for the murder of thousands of innocent men, women, and children," President Obama announced in a late-night address to the nation.

2012 -- Sandy Hook Elementary School mass shooting

On Dec. 14, 2012, Adam Lanza, 20, armed with a Remington AR-15 rifle forced his way into Sandy Hook Elementary School in Newtown, Connecticut, and in the course of 264 seconds, fatally shot 20 first graders and six staff members.

2013 -- Boston Marathon bombing

On April 15, 2013, two backpack bombs were detonated near the finish line of the Boston Marathon, killing three people and injuring more than 260 others in an incident that law enforcement officials deemed a terrorist attack. An intense investigation identified two brothers, 19-year-old Dzhokhar Tsarnaev and 26-year-old Tamerlan Tsarnaev, as the suspects. The older Tsarnaev died in a shootout with law enforcement officers, and his younger brother was captured after he survived being shot. Dzhokhar Tsarnaev was convicted in 2015 on multiple federal charges, including using and conspiring to use a weapon of mass destruction resulting in death, and was sentenced to death.

2014 -- Eric Garner and Michael Brown deaths

On July 17, 2014, Eric Garner, a 43-year-old Black man, died after a New York City police officer placed him in a chokehold, a maneuver that had been banned by the New York Police Department. A few weeks later, on Aug. 9, unarmed Black teenager Michael Brown was fatally shot by a white police officer in Ferguson, Missouri, setting off more than a week of protests and riots throughout Missouri and elsewhere. Both cases galvanized the Black Lives Matter movement launched in 2012 when Black teenager Trayvon Martin was fatally shot in Florida by neighborhood watch volunteer George Zimmerman.

2015 -- US Supreme Court rules in favor of gay marriage

In a historic decision, the U.S. Supreme Court ruled that the Constitution guaranteed a right to same-sex marriage in all 50 states. The 5-4 decision in Obergefell v. Hodges capped a long and often contentious battle over what many have called the "defining civil rights challenge of our time." The case behind the decision began in 2013, after the Supreme Court ruled that same-sex spouses must be afforded the same federal benefits as other married couples. That ruling, though, did not tackle the question of whether gay marriage is a constitutional right.

2016 -- Donald Trump elected president and Pulse nightclub mass shooting

On Nov. 8, 2016, real estate mogul and reality TV star Donald Trump won the presidential election as the Republican nominee, defeating former Secretary of State Hillary Rodham Clinton, the Democratic Party's nominee, and becoming the 45th president of the United States. Trump stunned observers by defying polling and pulling off a comfortable Electoral College victory despite losing the popular vote by millions.

Also in 2016, a man who swore allegiance to the leader of the Islamic State of Iraq and Syria, killed 49 people and wounded 53 others at the Pulse nightclub in Orlando, Florida, on June 12, a devastating day for the LGBTQ community. The gunman, 26-year-old Omar Mateen, was killed in a shootout with police.

2017 -- Las Vegas mass shooting and #MeToo movement

On Oct. 1, 2017, a former accountant opened fire from a window of a 32nd-floor suite at the Mandalay Bay Resort and Casino in Las Vegas, killing 53 people and wounding more than 850 others attending the outdoor Route 91 Harvest Festival music concert below. The killer, 64-year-old Stephen Paddock, died by suicide in the hotel suite, where investigators seized 24 guns, including AR-15 and AR-10 rifles with armor-piercing bullets.

After movie mogul Harvey Weinstein's first accusers came forward in October 2017, activists urged women to publicly share stories of sexual harassment and abuse they may have suffered at the workplace and at the hands of powerful men in the entertainment industry. The campaign was commonly referred to as the #MeToo Movement because the #MeToo hashtag was widely used on social media platforms as a way to connect the many stories being shared in separate posts.

2018 -- Mass shooting at Parkland school

On Feb. 14, 2018, a 19-year-old gunman killed 17 people and injured 17 others in a mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida. The gunman, Nikolas Cruz, pleaded guilty to 34 charges, including 17 counts of murder, in October 2021. A jury is currently being selected in the death penalty phase of his case.

2019 -- Trump's 1st impeachment and back-to-back mass shootings

On Dec.18, 2019, the House of Representatives voted to impeach President Donald Trump. The House's Democratic majority won passage of two articles of impeachment, accusing Trump of abuse of power for allegedly trying to strong arm Ukrainian President Volodymyr Zelenskyy to announce an investigation of his political opponent Joe Biden and obstructing Congress by allegedly directing White House staff and employees of other federal agencies not to comply with subpoenas. He was acquitted in his 2020 trial by the Republican-controlled Senate.

Two mass shooting occurred Aug. 4, 2019, one at an El Paso, Texas, Walmart store that left 23 people dead and 23 wounded, and the other in Dayton, Ohio, that left nine people dead, including the gunman's sister, and 17 wounded. The alleged gunman in the El Paso shooting, 21-year-old Patrick Crusius, who purportedly told investigators he allegedly set out to kill as many Mexicans as he could, was charged with multiple counts of capital murder and hate crimes and is awaiting a federal trial. The Dayton gunman, 24-year-old Connor Betts, was fatally shot by police.

2020 -- COVID 19 pandemic and George Floyd

In March of 2020, COVID-19 spread to United States causing thousands of deaths weekly and prompting a nationwide shutdown of most businesses.

Amid the worst U.S. health crisis since the 1918 influenza pandemic, George Floyd was killed on May 25 when Minneapolis police officer Derek Chauvin dug his knee into the back of the handcuffed and prone Black man's neck for more than nine minutes. The incident was captured on video by witnesses and posted to social media, sparking nationwide protests. Chauvin was convicted by a state jury on April 20, 2021, and sentenced to 22 1/2 years in prison. He pleaded guilty in December 2021 to federal charges of violating Floyd's civil rights and is awaiting sentencing.

2021 -- Capitol riot and Trump's 2nd impeachment

As Congress was in session to certify the election of Joe Biden as President of the United States, Trump supporters stormed the Capitol Building in protest of the election, breaching security causing a lockdown of the Capitol. Five people died during or after the attack, including four protesters and one Capitol Police officer, Brian Sicknick, and approximately 140 officers suffered injuries, according to the Department of Justice. More than 750 people have been arrested for their alleged roles in the melee, including many who have either pleaded guilty or have been convicted.

On Jan. 13, Trump became the first U.S. president to be impeached twice when he was charged with inciting the violent Jan. 6 insurrection at the U.S. Capitol. The then-Republican-controlled Senate voted 57-43 to acquit Trump, although seven Republican senators voted along with Democrats to convict him.

2022 -- Russia invades Ukraine

Russian President Vladimir Putin ordered his army invade Ukraine on Feb. 24. Since the war started, thousands of Ukrainian civilians have been killed and millions more have been displaced from their homes have fled the country to seek refuge.