It's one of the most-visited sites in the world, but YouTube didn't always plan on being an all-conquering video portal.

The platform was originally destined to be a dating site, designed for singles to upload videos of themselves talking about what they were looking for in a partner, according to co-founder Steve Chen, talking at South by Southwest in Texas.

"We always thought there was something with video there, but what would be the actual practical application?" he said. "We thought dating would be the obvious choice."