Addictions are vast and varied, however can perhaps be characterised and simplified by the following:
You no longer feel that you have the choice to stop
It ( the addiction) seems stronger than you
It also gives you a false sense of pleasure. Pleasure that invariably turns into pain or discomfort, physical, mental and or emotional.
"Addiction is not the fundamental problem, but the addicts desperate and doomed attempt to solve a problem, that of unbearable emotional pain, self loathing and emptiness"
Dr Gabor Mate