Alcohol is a liquid, an organic substance. It is a drug. The kind most consumed with the least side effects is called ethyl. Abuse leads to destruction of the liver, heart problems, and utter misery. Less destructive use is remarkably entertaining.
Alcohol comes in many forms. Some forms are tasty (wine, Jim Beam, beer). Some are remarkably nasty (cheap vodka).
In humans, alcohol causes dizziness, a general loss of inhibition(see seduction), physical pleasure, and unwanted children.