Vodka
Vodka is an alcoholic beverage that is primarily compressed of water and ethanol but sometimes contains impurities from the brewing method or added flavorings. Traditionally vodka is made from fermented potatoes and is 80-proof. It is a popular neutral solvant for tinctures.
In North America and Europe many brands purchase 190-proof grain alcohol in bulk then filter, dilute with water, and bottle the liquid.[1][2]
Alternatives
A study conducted on NPR's Planet Money revealed negligible differences in taste between various brands of vodka, leading to speculation as to how much branding contributes to the concept of "super premium vodkas".[3]
Depending on use, a cheaper and compareable alternative to vodka is distilling a sugar wash or purchasing an off brand 190-proof grain alcohol and diluting with distilled water to the desired proof.