FourierSeries, FourierTrigSeries, and FourierCoefficient are part of the Mathematica kernel.
FourierSinCoefficient and FourierCosCoefficient are now in the built-in Mathematica kernel.
DTFourierTransform has been renamed to FourierSequenceTransform.
InverseDTFourierTransform has been renamed to InverseFourierSequenceTransform.
The numerical functions, such as NFourierTransform, are still available in the Fourier Series Package.
The default value of the FourierParameters option has changed for all symbols previously available in the Fourier Series Package.
The default value of the FourierParameters option has changed for each function as described below.