Grape Varieties by Pierre Galet. Hatchette Wine Library, first published in Great Britain by Castell Illustrated, 2002.
This paperback book describes 36 well-known grape varietals in detail with beautiful photographs. Cultivated vines can be identified by their leaves and their grapes. Each section provides the vineyard profile, color, and taste, the location in the world and information on how to identify the varietal. This was the first book in my library and I still use it today.