DAVID GREENE, HOST:

Good morning. I'm David Greene. Today, YouTube users log a billion hours daily watching the site's many, many videos. But in 2005, there was just one - an 18-second clip of YouTube co-founder Jawed Karim standing in front of some elephants.

(SOUNDBITE OF YOUTUBE VIDEO, "ME AT THE ZOO")

JAWED KARIM: The cool thing about these guys is that they have really long trunks, and that's cool.

GREENE: That humble video, uploaded 15 years ago this week, has now been viewed over 90 million times. Transcript provided by NPR, Copyright NPR.