Persecution of Muslims means when people treat Muslims unfairly because of their religious beliefs. It can be anything from making it hard for Muslims to practice their religion, to actually hurting them. For example, worshipping Allah is an important part of being a Muslim, but if people are mean to Muslims while they pray or don't let them enter a mosque (a type of Muslim building where they pray), then that is persecution. Persecution also happens when people try to make Muslims do something against their religion, or when they hurt Muslims because they are different. It's very wrong to do this, and no one should be treated unfairly just because of what they believe.