20 February 2015 Last updated at 17:46 GMT
It's an important issue and it's vital that the subject is addressed to try to find out how to deal with it.
Jenny went to a Diana Award Anti-Bullying Ambassadors event at the Emirates Stadium, where some celebrities were running workshops for children on how to tackle bullies.
Hear from the likes YouTube stars Niki and Sammy, and musical duo Bars and Melody - plus a few other familiar faces!
Click here for a preview of the new Newsround special, How to Make Friends on Planet Earth.
All week on Newsround we've been talking about the issue of bullying, something that affects many people.