I shall present the reasons for this assertion and support the arguments by presenting simulations of (i) star formation triggered by colliding clouds and expanding nebulae (HII regions, stellar-wind bubbles and supernova remnants); (ii) the patterns of star formation in galaxies which result from triggered star formation; (iii) violent interactions between protostellar discs and the resulting genesis of binary systems and brown dwarves; and (iv) protostellar collapse induced by a sudden increase in external pressure. Where possible I will compare the results with observation.