The third edition of the SFPE Handbook of Fire Protection Engineering represents an update of existing material with the addition of some important new subject matter. The rapid assimilation of performance-based design in fire protection has underscored the importance of this handbook. While the process of performance-based design has been documented in detail, die fundamental knowledge base has remained fragmented. This handbook, as it has been from its inception, is a contribution toward documenting and integrating die theoretical and applied bases of fire safety engineering. The need for concise description of die theoretical basis of fire protection engineering in conjunction with material on engineering calculations and practice is clear. Significant effort was made to provide a more useful and direct link from some of the fundamental chapters to actual use in practice. Examples include a new chapter on calculation of heat fluxes to surfaces and new treatment of ignition phenomena.