Using the relatively simple example of a young and intra-oceanic island arc, the New Hebrides Arc, and following an order of increasing complexity, we show some examples of active margins in which the proximity of continental masses and past geological events have complicated the initial structure. The lesser Antilles Arc will be used as an example of a mature arc whose present structure results from the superimposition of several tectonic stages of evolution; in addition the close proximity of the South American continent to its southern tip has brought about considerable sedimentary influxes. To conclude, Mediterranean active margins will be used as an example of a continental collision zone resulting from the almost complete consumption of the oceanic crust initially present.