Potential threats

Cyber Bullying
Cyberbullying is the use of technology to harass, threaten, embarrass, or target another person. By definition, it occurs among young people. When an adult is involved, it may meet the definition of cyber-harassment or cyber-stalking, a crime that can have legal consequences and involve jail time.
Sometimes cyberbullying can be easy to spot — for example, if your child shows you a text message, tweet, or response to a status update on Facebook that is harsh, mean, or cruel. Other acts are less obvious, like impersonating a victim online or posting personal information, photos, or videos designed to hurt or embarrass another person. Some kids report that a fake account, web page, or online persona has been created with the sole intention to harass and bully.
Cyberbullying also can happen accidentally. The impersonal nature of text messages, IMs, and emails make it very hard to detect the sender's tone — one person's joke could be another's hurtful insult. Nevertheless, a repeated pattern of emails, text messages, and online posts is rarely accidental.
Spam
Spam is flooding the Internet with many copies of the same message, in an attempt to force the message on people who would not otherwise choose to receive it. Most spam is commercial advertising, often for dubious products, get-rich-quick schemes, or quasi-legal services. Spam costs the sender very little to send -- most of the costs are paid for by the recipient or the carriers rather than by the sender.
There are two main types of spam, and they have different effects on Internet users. Cancellable Usenet spam is a single message sent to 20 or more Usenet newsgroups. (Through long experience, Usenet users have found that any message posted to so many newsgroups is often not relevant to most or all of them.) Usenet spam is aimed at "lurkers", people who read newsgroups but rarely or never post and give their address away. Usenet spam robs users of the utility of the newsgroups by overwhelming them with a barrage of advertising or other irrelevant posts. Furthermore, Usenet spam subverts the ability of system administrators and owners to manage the topics they accept on their systems.
Phishing
Phishing is an e-mail fraud method in which the perpetrator sends out legitimate-looking email in an attempt to gather personal and financial information from recipients. Typically, the messages appear to come from well known and trustworthy Web sites. Web sites that are frequently spoofed by phishers include PayPal, eBay, MSN, Yahoo, BestBuy, and America Online. A phishing expedition, like the fishing expedition it's named for, is a speculative venture: the phisher puts the lure hoping to fool at least a few of the prey that encounter the bait.
Denial of service attacts(DOS attacks)
A denial of service (DoS) attack is an incident in which a user or organization is deprived of the services of a resource they would normally expect to have. In a distributed denial-of-service, large numbers of compromised systems attack a single target.
Although a DoS attack does not usually result in the theft of information or other security loss, it can cost the target person or company a great deal of time and money. Typically, the loss of service is the inability of a particular network service, such as e-mail, to be available or the temporary loss of all network connectivity and services. A denial of service attack can also destroy programming and files in affected computer systems. In some cases, DoS attacks have forced Web sites accessed by millions of people to temporarily cease operation.