Bullying can range from physical violence to verbal abuse and being cut out of social groups. It also includes abusive texts, e-mails or nasty notes put on web sites (known as cyber-bullying).
Bullying is not a one-off incident such as a fight or when two equals have the odd fight or quarrel.
Bullying is an abuse of power by one or more people through repeated hurtful or aggressive behaviour with the intention to cause emotional or physical harm to another person.
Whether you or someone you know is being bullied, or if you're the person doing the bullying, there are things you can do to stop it happening.
The first thing that you should do if you're being bullied is to tell someone about it - don't suffer in silence. You can tell a friend, a parent or a teacher at your school.
There are also a few things that you can do yourself that may make a person who bullies think twice about picking on you:
If you don't like seeing people being bullied, then do something about it. By not saying or doing anything, you're letting the person who bullies win and making the victim suffer for longer.
If you do want to do something, you can:
It's often just as hard for people who have bullied others to ask for help. You may be worried that no-one will take you seriously or you'll get into trouble by admitting you've bullied someone. But that's not the case.
Try and talk to a teacher or an older pupil that you get on well with and talk through the reasons behind your bullying. They'll be able to give you support and advice about how to stop your bullying.
If you want to talk to someone anonymously, try calling Childline - telephone: 0800 1111 - or the NSPCC. Although you may think that these organisations will only help victims, they're trained to help anyone in a confidential and non-judgmental way.
A lot of schools have an anti-bullying policy in place that aims to protect students against harassment and abuse. Try and get hold of a copy and bring it with you when you tell a teacher about the problems you're having.
Some schools also have older pupils who volunteer to be 'buddies' to victims of bullying. They can give advice and support, and give you another way of reporting cases of bullying if you're not comfortable with reporting your difficulties to another adult.
If you're not being bullied yourself, but you know that your school has a bullying problem and you want to do something about it, there are a number of organisations that you can contact to help you set up an anti-bullying scheme or network.