Is Stalking Illegal?

"Stalking Behavior" is a set of many behaviors (e.g., telephone harassment, sending unwanted gifts, pursuing, or surveillance).  
http://www.stalkingbehavior.com/

The act of stalking is often the culmination of several acts. Once they are all put together and used to harass or intimidate someone, then it rises to the level of stalking.

A course of conduct is a series of behaviors that when viewed collectively demonstrate a clear pattern. While some stalkers intend to cause fear in their victim,  In cases when the intent is not to cause fear, if the acts that ultimately did cause the fear are deliberate, then the standard is met. http://www.superpages.com/supertips/stalking.html