Why is waves crashing?

Could you elaborate on the phenomenon of waves crashing? What factors contribute to their formation and subsequent collision with the shoreline? Is it simply the result of gravity pulling the water back down to the ocean floor, or are there more complex forces at play? How do the size, shape, and angle of the waves influence their crashing behavior? Additionally, does the composition of the shoreline, such as rocky cliffs or sandy beaches, play a role in how waves crash? Understanding these aspects may provide insight into the intriguing dynamics of waves crashing.