Longitudinal Wave: A type of wave where the particle displacement is parallel to the direction of wave propagation.
Amplitude:The maximum extent of a vibration or displacement from the equilibrium position in a waveform.
Electromagnetic Wave: $$A \, type\,of\,wave\,that\,consists\,of\,oscillating\,electric\,and\,magnetic\,fields$$ $$that \, propagate \perpendicularly \to \each \other.$$