What does the word 'bin' mean in the context of FFT's?

Everywhere I read about the FFT, I read about frequency bins. I can't find anything about what is precisely meant with 'bin'. What I wonder about is if this is actually meant to imply that the FFT returns binned data in the sense of the word as used in statistics.

I think this question can be rephrased into this example: if I have bins centered at 1Hz, 2Hz, 3Hz, etcetera, what would happen to a frequency component at 2.4Hz? If the frequency bins are actually bins, I think this would mean that the amplitude is simply added to the 2Hz bin.

If the bins are indeed bins as I interpret the word, I would really like to know why the FFT results are binned. If not, then I am curious why they are called bins.

• Think of bins as a buckets to which you pour energy from infinite amount of possible frequency components. If this frequency is not matched with exact frequency bin then it smears leaks over rest of the bins. So in your case 2.4Hz will leak into other bins and your amplitude estimate will be not exact. Please read about spectral leakage.
– jojek
Mar 17 '15 at 11:37