The fft function computes the FFT of a specified signal.
In general, we will want to view either the magnitude or phase values of the FFT coefficients, which in Matlab can be determined using the abs and angle functions.
A variety of windows can be applied to a signal before the computation of the FFT using the functions hann, hamming, blackman. For a complete list, see the window function help. Time-domain windows can help minimize spectral artifacts related to signal truncation.
The spectrogram function computes a time-frequency plot of a signal where color represents spectral magnitude amplitude.