What do you mean by Bandwidth of a signal? Give its importance.

Hint: Bandwidth refers to the difference in upper and lower band of frequencies. It is measured in Hertz.

Complete step by step answer:
Bandwidth of a signal refers to the difference between upper band and lower band frequencies in a continuous band of frequencies.
Bandwidth basically refers to the range of frequencies over which an electronic circuit can operate nicely and without any disturbance.
For example, if an amplifier has a bandwidth of $2800Hz$ . That means this amplifier can amplify signals nicely (without any distortion within the range of $300Hz$ to $3100Hz$ . Beyond this range the amplification will be reduced drastically and will also be prone to distortion.

In communications systems, the signals through which messages are transmitted can be of various types, like, voice, music, picture or computer data. Each of these have specific frequency ranges referred to as bandwidth of that signal.
Bandwidth of speech signals: $2800Hz$ ( $3100Hz$ to $300Hz$ )
Bandwidth of video signals: about $4.2MHz$
Bandwidth of music signals: $20KHz(20KHz - 20Hz)$

Importance of Bandwidth of a signal:
i) Bandwidth of a signal determines the range of frequency in which the signal can be used without being distorted.
ii) Bandwidth of the signal also indicates the amount of data that can be transmitted within a given time. More the bandwidth, more data can be transmitted.

Thus, Bandwidth plays a vital role in determining the quality of signal at the same time denoting the suitable operating frequency ranges of a signal.

Note: Bandwidth has different meaning in different contexts, it refers to the frequency range on which a signal can operate properly in a communication system whereas in Computer system it refers to the amount of data transferred. Bandwidth plays an important role in communication systems, both wired and wireless.