What are the different types of noise in communication systems?

Noise types include: Thermal noise (Johnson noise, from random electron motion in conductors, white spectrum), Shot noise (from discrete charge carriers in semiconductors), Flicker noise (1/f noise, dominant at low frequencies), Intermodulation noise (from nonlinear mixing of signals), Crosstalk (interference from adjacent channels), and Atmospheric/cosmic noise (external interference). Thermal noise power = kTB (k=Boltzmann constant, T=temperature, B=bandwidth). System noise figure quantifies degradation from ideal performance.