Nobody has the right to hurt other people by hitting them, kicking them, calling them names, spreading rumors about them or by doing anything else which is intended to be upsetting.
Bullies try to justify their actions by saying that it is their victim's fault for being different. They may pick on someone who is tall or small, or fat or thin, or wears glasses, or has a different accent, or another religion, or is shy or clever, or good looking, or disabled or . . . Any excuse will do, and if there is no real difference then the bullies will invent one.
If this is happening to you tell yourself that it is not your fault, and that it is the bullies who need to change, not you.
What To Do
Talk to someone you can trust, a teacher, parent, older friend or relative.
Be persistent. If the first person you talk to ignores you don't give up, speak to someone else.
If you can, write down everything the bullies have done or have said to you, and try to write down how you feel. When you have found someone you can trust and who is helpful, discuss what you have written with that person. Be very careful to only write down things which really happen.
If you find it difficult to talk to an adult, ask one of your friends to come with you, or ask someone to talk to an adult on your behalf.
Most importantly, do something. Sometimes bullying stops quickly but doing nothing means it may continue until someone is seriously upset or hurt. That could be you, or the bullies may find new victims. If their behavior is not challenged they are unlikely to stop.
What Not To Do
Don't try to deal with the problem on your own- there is nothing wrong in asking for help.
Don't hit the bullies- you might end up being accused of bullying yourself
Always tell the truth about what has happened. Don't exaggerate. If a small part of what you are saying is shown to be untrue then it throws everything else into doubt.
Don't believe the lies that the bullies tell about you.
Don't hide what is happening from the adults you trust. Keeping things secret is the bullies' biggest weapon against you. That is why they go to so much trouble to try to stop you telling.