Vodka (Polish: wódka, Russian: водка) is a distilled liquor.

Vodka, one of the world's most popular liquors, is composed solely of water and ethyl alcohol with possible traces of impurities and flavorings. Vodka is made from any one of these fermented substances: grain, rye, wheat, potatoes, or sugar beet molasses.

Vodka’s alcoholic content usually ranges between 35 to 50 percent by volume; the standard Russian, Lithuanian, and Polish vodkas are 40 percent alcohol by volume (80 proof).

Historically, this alcoholic-proof standard derives from the Russian vodka quality standards established by Tsar Alexander III in 1894.
The Muscovite Vodka Museum reports that chemist Dmitri Mendeleev determined the ideal alcohol content as 38 percent; however, because in that time distilled spirits were taxed per their alcoholic strength, that percentage was rounded upwards to 40 percent for simplified taxation calculations.

For such a liquor to be denominated “vodka,” governments establish a minimal alcoholic proof; the European Union established 37.5 percent alcohol by volume as the minimal proof for European vodka.

Vodka is traditionally drunk neat in the vodka belt — Eastern Europe and Nordic countries — and elsewhere. It is also commonly used in cocktails and mixed drinks, such as the bloody Mary, the screwdriver, the White Russian, the vodka tonic, and the vodka martini.

Source: http://en.wikipedia.org/wiki/Vodka

Flavoured vodkas includes all spirits, which besides spirit and water additions includes aromatic substances, called aromatic - flavor admixture, giving them taste and odor characteristic for their species concerned. In addition, they contain mostly sugar and sometimes food coloring. Their power ranges from 20 to 75%.

Dry vodkas contains up to 5% of the extract

Natural vodkas are produced from raw wine spirits, grains, fruits, etc. thus requiring fermentation relevant raw material (grapes, fruits, cereals) and distillation of spirit arosed in mash.