Addictions

I had nothing to do hours ago so I decided to read about something random. I picked about "addiction."

According to Wiki,

addiction has been defined as physical and psychological dependence on psychoactive substances (for example alcohol, tobacco, heroin and other drugs) which cross the blood-brain barrier once ingested, temporarily altering the chemical milieu of the brain.

I've been wondering how it feels like to be addicted on alcohol, tobacco such as fuente cigars, heroin and other drugs. I wonder what's the life of those people who are dependent on this things.

Do you think addiction is okay? Do you think it's the opposite?