Modulation is necessary for the transmission of information, since electromagnetic waves of low (sound) frequency are of low intensity. Suppose, for example, a signal is transmitted. In modulation, you can change the amplitude of high-frequency oscillations with an audio frequency (amplitude modulation), or you can change the frequency (frequency modulation).
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.