Summarize this article:

The very instant someone threatens or scares you, you should use whatever tools the chatroom or social media site has to block that person. By blocking the person, you'll limit their ability to scare you. In the end, they'll probably move on to bothering other people. Perhaps the easiest way you can protect yourself is to log out of the chatroom if someone makes you feel uncomfortable. Cyberbullies, predators, and trolls immediately lose power over you when you log out. By logging out, you'll empower and safeguard yourself. If someone in a chatroom suggests that they are going to hurt you or someone else, if they threaten violence, or do anything that leads you to be suspicious of them, you should report them immediately. You can report them to the chatroom's moderator, the service the chatroom is hosted by, or the police. If someone online makes you uncomfortable, scared, or threatens you, you should tell someone immediately. Whether you're a teenager or an adult, your friends and loved ones will be able to give you guidance and perspective when it comes to the person who made you uncomfortable.  Remember, telling is not snitching or tattling. Ask your parents for help if online activity makes you uncomfortable. Talk to friends about what is going on online. Cyberbullying is the act of someone trying to intimidate you, make you feel bad, or simply harassing you. If someone commits cyberbullying against you or someone you know, you should report it to an adult or an appropriate authority. For a list of places to report cyberbullying, visit: https://cyberbullying.org/report. Cyber-violence includes pretending that the person knows everything about you and threatening to harm or kill you, your family, your friends or your pets.

Summary:
Block threatening or scary people immediately. Log off if you feel uncomfortable. Report suspicious activity. Tell others what is going on. Report cyberbullying.