A clear, colorless, unaged liquor, the name of which comes from the Russian zhiznennaia voda, "water of life." Vodkas can be made from everything from potatoes to beets, although those made from grain (primarily barley and wheat, sometimes rye or corn) are considered the best. Vodka's purity is the result of distillation at high proof levels, then filtration through activated charcoal to remove most remaining impurities that would contribute distinctive characteristics. Some vodkas are triple-filtered for ultimate purity. Even so, vodka connoisseurs note distinct flavor differences when vodkas are tasted at room temperature sans mixers. In general, however, vodka served straight should be served icy cold. Flavored vodkas, long common in Russia and Poland, may be flavored with anything from fruits to hot peppers. Some flavored vodkas are sweetened slightly.