A Scram jet is a jet which needs supersonic propulsion to take off. It is taken into air by another larger aircraft and is released in supersonic speed.
Most low flying fighter jets reduce speed in civilian areas (during peacetime) to around 450-500 mph.
A pulse jet engine is one of the most simple and efficient propulsion devices ever designed. There are three types of pulse jet engines: The valved pulse jet, the valveless pulse jet, and the upright or "Jam jar jet". For complete details on pulse jet engines, go to wikipedia.org and search "Pulse Jet Engine".
Jet fuel is injected into high pressure air in jet engines.
The Germans invented the first operational jet engine during WW2.