Some people continue to inspire, even after they've left us.
Sobiech lost his battle to a rare form of cancer this past May, but his legacy has continued to touch the hearts of people across the globe.
On Thursday night, a choir of about 5,000 singers came together to sing a triumphant version of "Clouds" at the Mall of America in Bloomington, Minn. The event, held one year after "Clouds" hit YouTube, was organized by local radio station, KS95.
In the crowd were Sobiech's parents, Laura and Rob Sobiech, and his girlfriend, Amy Adamle.
"Everybody came together, and it was for Zach, and it was for everyone in the room," Rob Sobiech told the Pioneer Press. "And it was for other kids who have cancer."
"I know [Zach is] smiling right now," Adamle added, "just like all of us are."
Watch the incredible performance of "Clouds" in the video above.