Frequency domain analysis is a method used to analyze signals by transforming them from the time domain into the frequency domain. This transformation allows us to see how much of the signal's energy is present at different frequencies. Common techniques for this transformation include the Fourier Transform and the Fast Fourier Transform (FFT). In the frequency domain, signals are represented as a sum of sinusoidal components, making it easier to identify patterns, noise, and other characteristics. This analysis is widely used in various fields, including signal processing, communications, and audio engineering, to improve system performance and design.