Drugs form a broad category of chemical substances that includes medicinal drugs or pharmaceutical drugs and other kinds of drugs, some of which are illegal or banned.
Drugs also include substances like alcohol, nicotine and caffeine. So by drinking wine or beer, smoking tobacco and even drinking coffee or tea, one is consuming drugs.
The best part? Sugar (or any other fructose-containing sweetener) can also be considered a drug, and an addictive one at that!
Some substances blur the distinction between medicinal drugs and illicit drugs, or can be both at the same time, or they can keep moving between these two categories over time. Examples are marijuana, ketamine, fentanyl and what seems to be a favourite of everyone on this site, sodium pentobarbital.