Westerly wind bursts (WWBs) are brief, anomalously westerly winds in the tropical Pacific that play a role in the dynamics of ENSO through their forcing of ocean Kelvin waves, yet their basic mechanism is not yet well understood. We analyze the temporal and spatial WWB characteristics and the momentum budget of different classes of WWBs. The goal is to understand their mechanism of excitation and decay and their links to extreme El Niño events. This has implications for both preindustrial and future climate simulations and observations. The improved understanding of WWBs may help us understand and project how El Nino events may change in a warmer climate, a problem still open despite decades of research.