This is the electromagnetic spectrum just above the visible light spectrum with higher energy (and higher frequency). This electromagnetic radiation is responsible for feeling the heat when you place your hand close to the side of a fire. It is also harnessed in night vision where bodies that emit some form of heat are visible due to their emission of IR.
Frequency refers to how many wave lengths pass in a second and speed is how fast the wave is traveling for example the speed of light goes really fast but has a mid-level frequency.
