All around the world, there are conspiracy theorists who believe the Earth is flat. And their community seems to be growing, judging by attendance at flat Earth conferences and events.

Flat Earthers say YouTube was key in helping them spread their message. One researcher found that of attendees at a flat Earth conference, nearly all said they first came to the idea through the video-sharing platform.

The Google-owned company says it's taking action to prevent conspiracy videos from reaching large numbers of people.

So how - and why - did YouTube enable the flat Earth community to grow?

Hear more about this story on the BBC Trending podcast.

Video journalist: Marco Silva

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