This book documents the experimental techniques developed to study flame microstructure and presents the results and understanding the studies have brought to the fields of combustion and high temperature processes. Premixed laminar flames are the simplest, and show the full range of combustion processes. They are ideal models for studying individual high temperature chemistries, physical processes, and their interactions, and are therefore used to illuminate the processes common to flames. Experimental methods for measuring and mathematical methods for analysing laminar flame structure are presented and the understanding of flame processes is stressed throughout.