As my team sifted through 10 years of historic imagery, I was struck by the amount of devastation and pain the world has endured: the Haiti earthquake, the Deepwater Horizon explosion and oil spill, Benghazi, Ebola, the constant school shootings in the United States, the Las Vegas massacre.
Then there are images calling for democracy and change: the Arab Spring, Venezuela, Hong Kong.
And there are pictures that mold public opinion and push governments to take action: the image of the Honduran toddler crying as her mother is detained near the US-Mexico border and, before then, the plight of 5-year-old Syrian refugee Alan Kurdi, washed ashore after drowning in the waters off southern Turkey.
I also can't help but be inspired by the courage shown by 17-year-old Emma Gonzalez, a school shooting survivor who has helped galvanize the call to action on gun control. I found the moment Serena Williams consoled Naomi Osaka at last year's US Open admirable, just moments after Williams pointedly argued with a chair umpire over a call that eventually cost her the championship.
And the latter part of the decade produced a string of storytelling images from Donald Trump's presidency, his administration and his policies.
All of these stories are woven together in this 100-picture report. Every image is iconic in its own merit, and they are sometimes taken by photojournalists in harm's way. Each photo is memorable, permanently capturing a moment in history, searing its significance and its oddity in our consciousness, oftentimes shaping public opinion and affecting policy.
We present to you the defining photos of the past decade.
Editor's note: This gallery contains graphic images. Viewer discretion is advised.