Q. Explain about Frequency domain?

Frequency domain:  Frequency domain is a term which is used to elucidate the domain for analysis of mathematical signals or functions with respect to frequency, instead of time. A time-domain graph demonstrates how a signal changes over time. While a frequency-domain graph shows how much of the signal lies within every given frequency band over a range of frequencies. A frequency-domain representation can also comprise information on the phase shift which should be applied to each sinusoid in order to be able to recombine the frequency components to recover original time signal.