Plasma-assisted ignition and combustion have been studied extensively for over a century, initially in internal combustion engines and spark ignition systems. Recent research has focused on non-equilibrium plasma for ignition and combustion control, offering new possibilities for efficient ignition and flame stabilization. The mechanisms of plasma-chemistry interaction, energy redistribution, and non-equilibrium initiation of combustion have been well understood, with various fuels examined using different discharge types. Several mechanisms affect gas when using a discharge to initiate combustion or stabilize a flame. Thermal mechanisms include gas heating leading to increased chemical reaction rates and inhomogeneous heating generating flow perturbations. Non-thermal mechanisms include ionic wind, ion and electron drift, and excitation, dissociation, and ionization of the gas, leading to non-equilibrium radical production and changes in ignition and combustion kinetics. These mechanisms can provide additional control for combustion in extreme conditions such as hypersonic flight. Hypersonic aircraft operating at Mach 6 and 30 km altitude can travel 13,000 km in under 2 hours, making them valuable for time-critical cargo and passenger transport. These vehicles operate in multiple engine cycles to reach scramjet speeds and can be used for space transportation. However, design challenges arise due to severe flight conditions, including high dynamic pressure and thermal loads. The flight envelope is limited by thermal and structural constraints, with lower and upper boundaries set by dynamic pressure and combustion efficiency, respectively. Scramjet engines operate in a dual-mode ramjet configuration for Mach 3-6 and switch to scramjet mode for Mach 7 and above. Plasma-assisted combustion is crucial for extending the engine stability region to low dynamic pressures and high Mach numbers. Recent experimental studies have demonstrated the efficiency of plasma-assisted ignition in various flow conditions, including supersonic, subsonic, and quiescent gas. These studies show that plasma can significantly reduce ignition delays and improve combustion efficiency, especially in lean mixtures. The physics of plasma-assisted combustion involves energy branching in discharge plasma, where electrons transfer energy to different molecular degrees of freedom. The reduced electric field E/n determines the energy distribution and the type of excitation. Different discharge types, such as arc, glow, and streamer discharges, have distinct characteristics in terms of energy deposition and excitation. The efficiency of plasma-assisted combustion depends on the ability to control the direction of energy deposition and the recombination of active particles. Vibrational relaxation is a slow process that can significantly affect chemical reactions, especially in the presence of hydrocarbons. Theoretical models have been developed to estimate reaction rates under non-equilibrium conditions, showing that vibrational excitation can significantly accelerate chemical reactions. These findings highlight the importance of understanding plasma-assisted combustion mechanisms for applications in hypersonic flight and other extreme environments.Plasma-assisted ignition and combustion have been studied extensively for over a century, initially in internal combustion engines and spark ignition systems. Recent research has focused on non-equilibrium plasma for ignition and combustion control, offering new possibilities for efficient ignition and flame stabilization. The mechanisms of plasma-chemistry interaction, energy redistribution, and non-equilibrium initiation of combustion have been well understood, with various fuels examined using different discharge types. Several mechanisms affect gas when using a discharge to initiate combustion or stabilize a flame. Thermal mechanisms include gas heating leading to increased chemical reaction rates and inhomogeneous heating generating flow perturbations. Non-thermal mechanisms include ionic wind, ion and electron drift, and excitation, dissociation, and ionization of the gas, leading to non-equilibrium radical production and changes in ignition and combustion kinetics. These mechanisms can provide additional control for combustion in extreme conditions such as hypersonic flight. Hypersonic aircraft operating at Mach 6 and 30 km altitude can travel 13,000 km in under 2 hours, making them valuable for time-critical cargo and passenger transport. These vehicles operate in multiple engine cycles to reach scramjet speeds and can be used for space transportation. However, design challenges arise due to severe flight conditions, including high dynamic pressure and thermal loads. The flight envelope is limited by thermal and structural constraints, with lower and upper boundaries set by dynamic pressure and combustion efficiency, respectively. Scramjet engines operate in a dual-mode ramjet configuration for Mach 3-6 and switch to scramjet mode for Mach 7 and above. Plasma-assisted combustion is crucial for extending the engine stability region to low dynamic pressures and high Mach numbers. Recent experimental studies have demonstrated the efficiency of plasma-assisted ignition in various flow conditions, including supersonic, subsonic, and quiescent gas. These studies show that plasma can significantly reduce ignition delays and improve combustion efficiency, especially in lean mixtures. The physics of plasma-assisted combustion involves energy branching in discharge plasma, where electrons transfer energy to different molecular degrees of freedom. The reduced electric field E/n determines the energy distribution and the type of excitation. Different discharge types, such as arc, glow, and streamer discharges, have distinct characteristics in terms of energy deposition and excitation. The efficiency of plasma-assisted combustion depends on the ability to control the direction of energy deposition and the recombination of active particles. Vibrational relaxation is a slow process that can significantly affect chemical reactions, especially in the presence of hydrocarbons. Theoretical models have been developed to estimate reaction rates under non-equilibrium conditions, showing that vibrational excitation can significantly accelerate chemical reactions. These findings highlight the importance of understanding plasma-assisted combustion mechanisms for applications in hypersonic flight and other extreme environments.