Like domestic violence, stalking is a crime of power and control. Stalking is conservatively defined as "a course of conduct directed at a specific person that involves repeated (two or more occasions) visual or physical proximity, nonconsensual communication, or verbal, written, or implied threats, or a combination thereof, that would cause a reasonable person fear."  Stalking behaviors also may include persistent patterns of leaving or sending the victim unwanted items or presents that may range from seemingly romantic to bizarre, following or laying in wait for the victim, damaging or threatening to damage the victim's property, defaming the victim's character, or harassing the victim via the Internet by posting personal information or spreading rumors about the victim.
According to the CDC's National Intimate Partner and Sexual Violence Survey (NISVS),1 in 6 women and 1 in 19 men have been stalked during their lifetime. For both female and male victims, stalking was often committed by people they knew or with whom they had a relationship. Two-thirds of the female victims of stalking (66.2%) reported stalking by a current or former intimate partner and nearly one-quarter (24.0%) reported stalking by an acquaintance. About 1 in 8 female victims (13.2%) reported stalking by a stranger. 
Stalking can be carried out in person or via electronic mechanisms (phone, fax, GPS, cameras, computer spyware, or the Internet). Cyberstalking—the use of technology to stalk victims—shares some characteristics with real-life stalking. It involves the pursuit, harassment, or contact of others in an unsolicited fashion initially via the Internet and e-mail. Cyberstalking can intensify in chat rooms where stalkers systematically flood their target's inbox with obscene, hateful, or threatening messages and images. A cyberstalker may further assume the identity of his or her victim by posting information (fictitious or not) and soliciting responses from the cybercommunity. Cyberstalkers may use information acquired online to further intimidate, harass, and threaten their victim via courier mail, phone calls, and physically appearing at a residence or work place.
Although cyberstalking does not involve physical contact with a victim, it is still a serious crime. The increasing ubiquity of the Internet and the ease with which it allows others unusual access to personal information, have made this form of stalking ever more accessible. Potential stalkers may find it easier to stalk via a remote device such as the Internet rather than to confront an actual person. Conduct that falls short of the legal definition of stalking may in fact be a precursor to stalking and must be taken seriously.  As part of the Violence Against Women Reauthorization Act of 2005, Congress extended the Federal interstate stalking statute to include cyberstalking (18 U.S.C. §2261 A).
[note 1] Tjaden, Patricia and Nancy Thoennes. Stalking in America: Findings From the National Violence Against Women Survey. Washington, DC: U.S. Department of Justice, National Institute of Justice, 1998, NCJ 169592.U.S.
[note 2] Black, M.C., K.C. Basile, M.J. Breiding, S.G. Smith, M.L. Walters, M.T. Merrick, J. Chen, and M.R. Stevens, "The National Intimate Partner and Sexual Violence Survey (NISVS): 2010 Summary Report," Atlanta, GA: National Center for Injury Prevention and Control, Centers for Disease Control and Prevention, 2011.
[note 3] Department of Justice. "Cyberstalking: A New Challenge for Law Enforcement and Industry: A Report From the Attorney General to the Vice President." Washington, DC: U.S. Department of Justice, 1999, NCJ 179575.