Why do we need convolution?

[aslamzohaib]

Well it may be sounding an elementary level question to the liking of few people here. But still i would like to know why do we know convolution? I've searched the forums but haven't got the desired result.

 

[Aya2002]

the effect of the channel on any input signal is the convolution process.

 

[amraldo]

Output = Input convoluted by system response
It is how the system processes the input to produce the output