The world was forever changed 20 years ago when terrorists from the militant terrorist organization Al-Qaeda hijacked four planes on Sept. 11, 2001.

The 9/11 attacks claimed the lives of 2,996 people and left thousands injured. Saturday marks the 20-year anniversary of the attacks on the World Trade Center in New York City, the Pentagon in Virginia, and Flight 93, which crashed in Pennsylvania and killed 44 people.

Although the attacks sent a wave of heartbreak across the nation, they also brought the country together.

In remembrance of 9/11, look back on a few quotes compiled from Success and Parade.

  • “Even the smallest act of service, the simplest act of kindness, is a way to honor those we lost, a way to reclaim that spirit of unity that followed 9/11.” — Barack Obama
  • “The attacks of September 11th were intended to break our spirit. Instead, we have emerged stronger and more unified. We feel renewed devotion to the principles of political, economic, and religious freedom, the rule of law, and respect for human life. We are more determined than ever to live our lives in freedom.” — Rudolph Giuliani
  • “Time is passing. Yet, for the United States of America, there will be no forgetting September the 11th. We will remember every rescuer who died in honor. We will remember every family that lives in grief. We will remember the fire and ash, the last phone calls, the funerals of the children.” — George W. Bush
  • “When Americans lend a hand to one another, nothing is impossible. We’re not about what happened on 9/11. We’re about what happened on 9/12.” — Jeff Parness
  • “Ten years have passed since a perfect blue sky morning turned into the blackest of nights. Since then we’ve lived in sunshine and in shadow, and although we can never unsee what happened here, we can also see that children who lost their parents have grown into young adults, grandchildren have been born and good works and public service have taken root to honor those we loved and lost.” — Michael Bloomberg
  • “Remember the hours after Sept. 11 when we came together as one! It was the worst day we have ever seen, but it brought out the best in all of us.” — John Kerry
  • “We didn’t crumble after 9/11. We didn’t falter after the Boston Marathon. But we’re America. Americans will never, ever stand down. We endure. We overcome. We own the finish line.” — Joe Biden
  • “If we learn nothing else from this tragedy, we learn that life is short and there is no time for hate.” —Sandy Dahl, wife of Flight 93 pilot Jason Dahl
  • “September 11 impressed upon us that life is a precious gift…. And I think we all have a duty to devote at least a small portion of our daily lives to ensuring that neither America nor the world ever forgets September 11.” — Bill Frist
  • “You can be sure that the American spirit will prevail over this tragedy.” — Colin Powell
9/11
Smoke pours from the twin towers of the World Trade Center after they were hit by two hijacked airliners in a terrorist attack in New York City, Sept. 11, 2001. Getty Images/ Robert Giroux