Chatrooms

Questions:

• Are there any issues I should be aware of, to safeguard myself when using social networking sites such as Facebook/Twitter?
• Are there any safety features on Facebook that can be used if my child comes across any offensive material or dubious communication?
• Is it safe for my child to use a chatroom?
• Someone is posting false information about me on Facebook/Twitter/a social networking site. Is this a criminal offence?
• Someone is sending me threatening / abusive / offensive messages via a social networking site. Is this a criminal offence?