To be called tequila, the liquor must be made from at least 51% blue agave, a Mexican succulent plant. It can then be combined with liquor distilled from sugar cane or other raw materials. The finest tequila is distilled from 100 percent blue agave and categorized by how long it's aged. Plata tequila, also known as white or silver, isn't aged at all, and its clean, peppery flavor is ideal in margaritas. Reposado tequila is aged in oak for between 2 and 11 months, so it's mellower and sweeter. Anejo tequila, the most refined, is aged for at least 1 year in oak, making for a smooth, aromatic tequila that's best served neat, like good whiskey or brandy.