The focus of this book is on modern processing techniques for radar detection. In this context, the effectiveness of a radar system is measured by its ability to distinguish the target from the clutter and/or other kind of interference. In order to improve the detection capabilities in practical scenarios, radar systems often process several pulses while the antenna beam is pointed at a target. In this case, the time taken to transmit (and receive) the N pulses used for detection (see also Chapter 2) is called dwell time. If these pulses are coherently integrated (i.e., both the amplitude and the phase of the received signals are used in the processing so that the signal contributions can be made to add in phase with one another), the time duration of the processing is often called coherent processing interval.