One in three social media users have made friends with strangers
9 February 2016 Last updated at 06:59 GMT
More than a third of 10-12 year olds with a social media account have made friends on social media that they've not met in person, according to a Newsround survey.
That's despite rules for many saying you need to be 13 or over to sign up.
So what experiences have some of you had on social media?
Leah spoke to a group of Year 7 pupils in Sunderland, in the north-east of England, to find out.