A lot of people from engineering and non-engineering departments have trouble with the frequency domain. Many people can show you the frequency domain representation of a time domain signal, but not many can tell you what it means physically or visually. If the best teacher is experience, then no one will have a clue of what lies in the physical representation of the frequency domain. This is mainly because no one thinks in terms of frequency. If a signal is shown to you in the time domain (for example, a rectangular pulse) it is much easier to think of it as just a rectangular signal and not as anything else. This article will show you how to better understand the frequency-domain representation of a signal with as little mathematics as possible, and also show you why it is more convenient in a lot of cases to use the frequency domain for signal analysis.