Watch out for those online sources (ie. websites on the internet) that appear to tell people that the very last 'bin' or frequency point in a FFT plot is exactly associated with the frequency 'fs' (the sampling frequency).
The right-most point in an FFT plot usually represents a frequency of [(N-1)/N] * fs.
N is the number of time domain sampling points. However though, for relatively large 'N', that last frequency is almost the same as "fs".
The gap (frequency resolution) between adjacent frequency points (ie. between two bin frequencies) is equal to fs/N.
So.... if we have N = 100 time domain sample points, then the FFT magnitude plot has 0 to 99 frequency points (ie. still a total of 100 points). Point number [ 0 ] represents 0 Hz (ie. DC). Point number  represents a frequency of 5 * gap = 50*fs/100 = fs/2 (ie. half the sampling frequency).
The entire FFT MAGNITUDE plot will look symmetrical about point . Normally, ignore the stuff above the half-way point, ie. point . So, when discussing the magnitude spectrum, bin [ 0 ] to bin  are generally the bins (or frequency points) of interest, which represents 0 Hz up to fs/2, with frequency gaps of fs/N between adjacent points.