system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is it exactly that alcoholics become addicted to?

I can understand addictions like Gambling, drugs and food, because the experience is a high. Alcohol is a depressent though, so I've never understood why people feel compelled to drink. Is it purely chemical, or is it conditioning from past good experiences (like drinking at parties etc)?
gpt
There are several types of addictions.

* Social addiction; a mental addiction,  to the atmosphere or social interactions associated with alcohol or venues/situations where alcohol is served. Can be parties, night clubs, sportspubs, or whatever.  
Alcohol often used as a social lubricant or catalyst, or to reinforce the emotions, but for some people in this category it may even be something that's just "forced" upon them since it's just "expected" to drink in the situations.

* Mental addiction; Drinking to get away. Keeping your mind on something else than... something.    
A way of "fleeing reality" and responsibility...   
(For some, simply being afraid of the since long postponed hangover.)
Not necessarily drinking alone, that's just the stereotype.

* Physical addiction; after a long time of abuse, the body "adjusts" and doesn't work properly without alcohol.  
Various byproducts from metabolic breakdown of ethanol accumulates in the body, but is being "kept in check" by the constant refill of alcohol.   
Sudden abstinence may cauce hallucinations, severe nausea,  convulsions, vomiting, etc... May be life threatening in severe cases.

Often some type of combination. An addicted person may have a little bit of *this* and a little bit of *that*. Of course there are also other types and subsets of alcohol dependency, but well...