Chapter 6 deals with laminar premixed flames. It starts with the derivation of Rankine–Hugoniot relations. Then flame structure is described at hydrodynamic, diffusive and reaction length scales. The concept of flame speed is introduced, and some common methods of determination of flame speed are discussed. Expressions for flame thickness and flame speed are derived for a planar adiabatic one-dimensional flame. The concepts of quenching distance and minimum ignition energy are derived. Towards the end of the chapter, an expression for flame stretch is derived assuming thin flames. Finally, the concepts of flame stability, lift-off, flashback and blowout are introduced and their importance in design of fuel flexible burners are discussed.