We're all using social media more and more, which means a fake news story can quickly spread among lots of people. Fake reports are also hard to spot when you see so many people agreeing with them.
Scientists have tested using a warning message about fake news on 2000 participants. They found that those who read the message were less likely to believe the fake stories shown to them afterwards.
I'd like to see warnings like this appear online. It may seem obvious, but it's very easy to forget that not everything you read online is true.