This book presents a unique design approach and utilization of a novel digital gates family known as Dual Mode Logic (DML), which enables an on-the-fly trade-off between high performance (Dynamic mode) and energy efficient (Static mode) operation. The book covers all aspects of DML methodology, starting from basic concepts, through single gate optimization, general module optimization, design trade-offs and new ways in which DML can be integrated into standard design flows, using standard EDA tools. The authors describe how DML logic can be used for many applications and in particular for ultra-low power, high performance, secure and reliable systems. After presenting the basic concepts of DML operation and a detailed exploration of design tradeoffs and optimization methods, the authors show how DML modes of operation can be controlled on the fly from the architecture to the gate levels. They also provide a detailed analysis of DML compatibility to standard design flows. The manuscript concludes with some exemplary advanced process nodes and technologies manufactured test-cases to direct a discussion on the potential of DML for the future.