Book excerpt: This is the definitive and complete guide to spread trading in futures. Covers spread trading methods -- analyzing spreads and spread price action, as well as discovering and executing profitable spread trades. Brings together various methods, such as analyzing prices combined with analyzing historical data on commodity price trends. Offers information on the following topics: Why Spread Prices Change, Carrying Charges, Historical Comparison Analysis, Seasonal Analysis, Chart Analysis, The Trading Plan, Trading Techniques, Sources of Information. This is a completely revised, updated, and expanded version o: Smith's earlier book, Commodity Spreads.