Stalking

One definition of stalking is 'a constellation of behaviours in which an individual inflicts upon another repeated unwanted intrusions and communications' (Mullen, 1999). (source- http://www.bbc.co.uk/insideout/yorkslincs/series7/stalking_advice.shtml)
In my opinion there are different levels of stalkish behaviour. For instance, simply watching someone you like whenever they are in the same room is very different from following them home and peering into their windows while they are in the shower.
Some may argue that it hurts the victim psychologically, however I argue that if they are unaware of this behaviour then it can not be hurting them. Though, saying this, I do not condone the behaviour.
It could be argued that the paparazzi 'stalk' celebrities to get a publishable picture of them, following them from place to place, however the law doesn't inflict restraining orders upon them, unlike 'crazed stalker fans' that do similar things.
It is also often assumed that men stalk women more often than the other way around, this is showed in films, television shows and even music videos such as Justin Timberlake's 'Cry me a river.'