It is tough to determine the moderate drinking level as the limit and consumption style of this drinking varies from man to man. For someone it is lowest in quantity and for someone it depends on the situation. If we quantify then it be more convenient to come up with a better definition.
For example, modern drinking stands for per day having a drink for one time. It is very important because during drinking sometimes we loose our mind and keep drinking. It is very harmful for the health. Keeping the health related issues in mind, this term was being coined.
Sometimes many people confuse this with social drinking. It is something which is accepted by the society and the individual continues with it.
In some countries a law is there to set the limit of moderate drinking. They set the minimum level of consumption and based upon it they determine others? one. Drinking is pretty harmful for body. You should not consume it beyond the minimum cutoff point. There are some people out there who treat drinking as like everyday meal. They are some how dependent on it they can not consume it in fewer times. They are likely to be addicted to this. They do not think about the future consequences of this extra consumption and they keep doing it until something hits their brain. It may be total damage of the body and mind etc.
Moderate drinking is useful in getting rid of these. As in this, you will have less consumption and here the intensity is lower than average. So it does not seem to as harmful as the usual drinking. It has mental advantages too. It helps to reduce the strain level and promote active part. So it is really a viable option to have moderate drinking.