Combustible mixtures can be ignited by various ignition sources. Within the research group FOR 1447 five important ignition sources shall be examined varying from hot surfaces to hot free jet flows. Concerning typical applications in the field of safety engineering, the ignition process can be influenced by different transport processes, which normally disturb the ignition via heat losses etc. In the case of hot surfaces the autoignition of a combustible mixture is mainly dominated by chemical reactions. The influence of perturbations on the ignition process becomes more and more important considering hot particles, mechanical sparks, electrical discharges or hot free jet flows as ignition sources. Additionally, various transport processes like molecular transport, laminar flow, and turbulent flow have to be considered. The ignition delay times of the combustible mixtures have to be reduced to compensate the losses, and sufficient energy has to be delivered from the ignition sources.