Similarly, I like how any LTI system is just poles and zeroes in the s-plane. Or, if your system is sampled (DSP, and actually most signals you'll deal with in

Similarly, I like how any LTI system is just poles and zeroes in the s-plane. Or, if your system is sampled (DSP, and actually most signals you'll deal with in a computer), in the z-plane. But not just every LTI system, ever sampled signal is poles and zeroes in the z-plane. I have used that fact for years, and it still blows me away from time to time. Laplace and z-transforms are pretty magical, more so than Fourier even (which is basically a special case).