Detection is referred to as coherent detection or coherent demodulation. A radar system will declare detection with a certain probability of detection if the received voltage signal envelope exceeds a pre-set threshold value. For this purpose, the radar receiver is said to employ an envelope detector. This chapter discusses target detection which was introduced in the context of single pulse detection with completely known amplitude and phase in one case, and known amplitude with random phase in another. A few sources in the literature refer to the M-out-of-N detection as binary integration and/or as double threshold detection; nonetheless, M-out-of-N is the most commonly used name. Multiple returned pulses can be integrated coherently or non-coherently. Pulse integration can be performed on the quadrature components prior to the envelope detector. The number of returned pulses from a given target depends on the antenna scan rate, the antenna beamwidth, and the radar PRF.