Anonymity is when someone makes threatening comments to you, but is able to hide who they are. This means that it can be hard for you to figure out who sent you a threatening message or email.
Anonymity can include the use of aliases or pseudonyms. Have a look at the book on pseudonyms on the bookcase.

Anonymity is a big issue in terms of cyberbullying. When a website was set up to humiliate Greg Frawley (check out the messages on the mobile phone – on the desk in the office), the police were unable to find the people responsible, as they had set up the website anonymously.

If someone is sending you threatening text messages on your mobile phone, unless you recognise the phone number it is sent from, you're unlikely to know who sent you the message. Or they may use someone else's phone to send you the message. These are examples of anonymity, where the bully’s identity remains hidden.