All liquors are based on alcohol, but it is also possible to buy pure alcohol separately. It is then usually known as pure grain alcohol (PGA) or grain neutral spirits (GNS).
Alcohol for human consumption is the same as ethyl alcohol (ethanol), usually distilled from grain, potatoes or fruit (see warning below). Pure alcohol is about 190 proof, but alcohol bought in stores is usually diluted with distilled water (Vodka is pure alcohol diluted to 80 proof).
Alcohol is a the main ingredient in homemade liqueur, but is sometimes used in punches. If you cannot get pure alcohol, Vodka is an alternative.
Note: Pure alcohol is very irritating to the throat and should never be drunk straight. Because it lack flavor, color and odor the is is very potent, even if the drinker may not be aware of this.
Warning: Never drink anything else than ethyl alcohol (ethanol). Methyl alcohol (wood alcohol/methanol) and isopropyl (rubbing) alcohol is toxic to the human body and may be lethal or cause serious brain damage.