Internet Addiction(Does it exist or not?)

I have recently discovered through some observation of both freinds and myself that one can be addicted to the net as a smoker is to the cigarrate.

This, as to my observation just happens without the person knowing that "ok am net addict",but as a smoker feels when he/she doesn't smoke for may be an hour a net addict feels that something is missing from him/her when he/she doesn't surfe the net for aday depending on the level of addiction of the person.

Now my question is, Is there anything like net addiction? Does it really exist? How do you feel as a net addict when you don't browse for a whole day?