Cyberstalking is the use of the Internet or other electronic means to stalk or harass an individual, a group of individuals, or an organization. It may include false accusations, monitoring, making threats, identity theft, damage to data or equipment, the solicitation of minors for sex, or gathering information in order to harass. The definition of "harassment" must meet the criterion that a reasonable person, in possession of the same information, would regard it as sufficient to cause another reasonable person distress.
Stalking is a continuous process, consisting of a series of actions, each of which may be entirely legal in itself. Lambèr Royakkers writes that:
"Stalking is a form of mental assault, in which the perpetrator repeatedly, unwantedly, and disruptively breaks into the life-world of the victim, with whom he has no relationship (or no longer has), with motives that are directly or indirectly traceable to the affective sphere. Moreover, the separated acts that make up the intrusion cannot by themselves cause the mental abuse, but do taken together (cumulative effect)."
CyberAngels has written about how to identify cyberstalking:
When identifying cyberstalking "in the field," and particularly when considering whether to report it to any kind of legal authority, the following features or combination of features can be considered to characterize a true stalking situation: malice, premeditation, repetition, distress, obsession, vendetta, no legitimate purpose, personally directed, disregarded warnings to stop, harassment, and threats.
A number of key factors have been identified:
- False accusations. Many cyberstalkers try to damage the reputation of their victim and turn other people against them. They post false information about them on websites. They may set up their own websites, blogs or user pages for this purpose. They post allegations about the victim to newsgroups, chat rooms or other sites that allow public contributions, such as Wikipedia or Amazon.com.
- Attempts to gather information about the victim. Cyberstalkers may approach their victim's friends, family and work colleagues to obtain personal information. They may advertise for information on the Internet, or hire a private detective. They often will monitor the victim's online activities and attempt to trace their IP address in an effort to gather more information about their victims. 
- Encouraging others to harass the victim. Many cyberstalkers try to involve third parties in the harassment. They may claim the victim has harmed the stalker or his/her family in some way, or may post the victim's name and telephone number in order to encourage others to join the pursuit.
- False victimization. The cyberstalker will claim that the victim is harassing him/her. Bocij writes that this phenomenon has been noted in a number of well-known cases.
- Attacks on data and equipment. They may try to damage the victim's computer by sending viruses.
- Ordering goods and services. They order items or subscribe to magazines in the victim's name. These often involve subscriptions to pornography or ordering sex toys then having them delivered to the victim's workplace.
- Arranging to meet. Young people face a particularly high risk of having cyberstalkers try to set up meetings between them.
Cyberstalkers meet or target their victims by using search engines, online forums, bulletin and discussion boards, chat rooms, and more recently, through online communities such as MySpace, Facebook, Bebo, Friendster, Twitter, and Indymedia, a media outlet known for self-publishing. They may engage in live chat harassment or flaming or they may send electronic viruses and unsolicited e-mails.  Victims of cyberstalking may not even know that they are being stalked. Cyberstalkers may research individuals to feed their obsessions and curiosity. Conversely, the acts of cyberstalkers may become more intense, such as repeatedly instant messaging their targets. 
More commonly they will post defamatory or derogatory statements about their stalking target on web pages, message boards and in guest books designed to get a reaction or response from their victim, thereby initiating contact.  In some cases, they have been known to create fake blogs in the name of the victim containing defamatory or pornographic content.
When prosecuted, many stalkers have unsuccessfully attempted to justify their behavior based on their use of public forums, as opposed to direct contact. Once they get a reaction from the victim, they will typically attempt to track or follow the victim's internet activity. Classic cyberstalking behavior includes the tracing of the victim's IP address in an attempt to verify their home or place of employment. 
Some cyberstalking situations do evolve into physical stalking, and a victim may experience abusive and excessive phone calls, vandalism, threatening or obscene mail, trespassing, and physical assault. Moreover, many physical stalkers will use cyberstalking as another method of harassing their victims.
The current US Federal Anti-Cyber-Stalking law is found at 47 USC sec. 223.
The first U.S. cyberstalking law went into effect in 1999 in California. Other states include prohibition against cyberstalking in their harassment or stalking legislation. In Florida, HB 479 was introduced in 2003 to ban cyberstalking. This was signed into law on October 2003. 
Some states in the U.S. have begun to address the issue of cyberstalking:
- Alabama, Arizona, Connecticut, Hawaii, Illinois, New Hampshire, and New York have included prohibitions against harassing electronic, computer or e-mail communications in their harassment legislation.
- Alaska, Florida, Oklahoma, Wyoming, and California, have incorporated electronically communicated statements as conduct constituting stalking in their anti-stalking laws.
- Texas enacted the Stalking by Electronic Communications Act, 2001.
- Missouri revised its state harassment statutes to include stalking and harassment by telephone and electronic communications (as well as cyber-bullying) after the Megan Meier suicide case of 2006.
- A few states have both stalking and harassment statutes that criminalize threatening and unwanted electronic communications.
- Other states have laws other than harassment or anti-stalking statutes that prohibit misuse of computer communications and e-mail, while others have passed laws containing broad language that can be interpreted to include cyberstalking behaviors
Cyberstalking has also been addressed in recent U.S. federal law. For example, the Violence Against Women Act, passed in 2000, made cyberstalking a part of the federal interstate stalking statute. Still, there remains a lack of legislation at the federal level to specifically address cyberstalking, leaving the majority of legislative prohibitions against cyberstalking at the state level.
Most stalking laws require that the perpetrator make a credible threat of violence against the victim; others include threats against the victim's immediate family; and still others require the alleged stalker's course of conduct constitute an implied threat. While some conduct involving annoying or menacing behavior might fall short of illegal stalking, such behavior may be a prelude to stalking and violence and should be treated seriously.
Online identity stealth blurs the line on infringement of the rights of would-be victims to identify their perpetrators. There is a debate on how internet use can be traced without infringing on protected civil liberties.
In Australia, the Stalking Amendment Act (1999) includes the use of any form of technology to harass a target as forms of "criminal stalking."
In Spain, it is possible to provide information about cyber-crime in an anonymous way to four safety bodies:
- Grupo de Delitos Telemáticos of the Civil Guard (Spain)
- Brigada de Investigación Tecnológica of the National Police Corps of Spain
- Mossos d'Esquadra in Catalonia
- Ertzaintza in Euskadi
- Computer crime
- Convention on cybercrime
- Harassment by computer
- Hate group
- Internet fraud
- Online dating
- Online predator
- ToS violation
- Bocij, Paul. Cyberstalking: Harassment in the Internet Age and How to Protect Your Family. Praeger, 2004, p. 14.
- Royakkers 2000:7, cited in CyberStalking: menaced on the internet
- Bocij, Paul. Cyberstalking: Harassment in the Internet Age and How to Protect Your Family. Praeger, 2004, pp. 9-10.
- Fighting Cyberstalking
- An exploration of predatory behavior in cyberspace: Towards a typology of cyberstalkers by Leroy McFarlane and Paul Bocij
- Bocij, Paul. Cyberstalking: Harassment in the Internet Age and How to Protect Your Family. Praeger, 2004, pp. 12-13.
- Compulsions in Depression: Stalking by Text Message - HOWES 163 (9): 1642 - Am J Psychiatry
- Types of Stalkers and Stalking Patterns
- Cyber-Stalking: Obsessional Pursuit and the Digital Criminal
- Look Who’s Googling: New acquaintances and secret admirers may already know all about you
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- Cybertelecom :: Cyberstalking Federal Internet Law & Regulation