In basic terms, Tolerance = the body's resistance to the effects of any drug. For instance, with prolonged, or excessive,
or inappropriate antibiotic use a virus in the body can and often does develop a resistance to the effects of the antibiotic.
This does happen and to get the desired benefit and impact on an illness like an STD the physician would have to prescribe
a stronger and more potent antibiotic. In the extreme case, the illness can become completely resistant to known drugs - an
obviously serious and deadly scenario.
So then, in the early years at the beginning of drinking, the body has no tolerance to the drug alcohol. A small amount,
1-2 beers can produce significant mood change and inebriation. The drinker "catches a buzz". As drinking continues
over time the body begins to develop more tolerance (resistance) to the effect and thus more alcohol is required to get the
desired effect (mood change). Most people drink for the effect (the mood change) not for the taste.
This happens gradually and the drinker generally is not very aware that they are now drinking more on each drinking occassion.
Over years the amount taken per drinking occassion continues to increase and at some point in time, the cells of the body
change because of being continually bathed in Alcohol and at that point - addiction occurs. When addiction occurs, tolerance
receeds, usually very rapidly.