The Fourier series expresses a periodic signal as a combination of sinusoidal waves, meaning the signal is made up of a combination of sine waves. The Fourier transform is a formula that transforms a signal recorded in time or space into its frequency components. It can process out noise from a signal to reveal the underlying frequencies, making the Fourier transform very good at filtering noise. The Fourier transform can operate on a function of either time f(t) or space f(x).