The difficulties associated with precisely defining this term (or defining it at all) are well documented. It seems to have been first applied to the harassment (in a general sense) of celebrities by strangers who were described as being obsessed. This use of the word appears to have been coined by the tabloid press in the United States.
Stalking can be defined as the willful and repeated following, watching, and / or harassing of another person. Most of the time, the purpose of stalking is to attempt to force a relationship with someone who is unwilling or otherwise unavailable. Unlike other crimes, which usually involve one act, stalking is a series of actions that occur over a period of
time. Although stalking is illegal, the actions that contribute to stalking are usually legal, such as gathering information, calling someone on the phone, sending gifts, emailing or instant messaging. Such actions by themselves are not usually abusive, but can become abusive when frequently repeated over time.