A Band-limited signal is defined as a signal whose Fourier Transform is zero above a specified frequency. Shannon Sampling Theorem is also stated for a strictly band-limited functions,i.e,
"For a band-limited case, 2W numbers per second are sufficient."
Where, "W" is the max. frequency content.
My confusion is that why band-limit a signal? What would be the situation if a signal is not perfectly band-limited?
My understanding says that unless we have a band-limited signal, we can't get a usable "W" and aliasing would also occur. Does it make sense as an answer?
I think I know answers intuitively, but struggling to frame it in words. Please guide me.