In this chapter, the authors discuss zero-padding commonly occurs, and the discrete Fourier transform (DFT) computed from the zero-padded signal may not contain the original DFT. While in theory they can eliminate leakage by sampling a given signal for an integer number of periods, this cannot be easily accomplished in practice when they attempt to analyze samples from an unknown signal because they would not know its period. The authors explain there are a number of different ways to formulate the DFT depending on the sampling period and sample size. In view of the symmetry in the formulation of DFT and inverse DFT, it is expected that zero padding the DFT will lead to signal interpolation in the time domain.