It would be difficult to explain this system in a few lines. Dowry system is entwined in our culture so much that although we know it's incorrect or illegal, we still give and take.
There is a perception that the dowry cases and the incidence is 'apparently' on the decrease, this would be attributable to increased education among women, women being employed more often, awareness of their rights, a proactive stance by the bride and her family etc.
But to me, dowry system still prevails within closed discussion, it may not be just exchange of cash but includes a series of events that are need for the new family to lead a better life'. Under this guise many demands are made indirectly (a car, contribution to husband's business ventures, part funding of a house or a plot of land, ornaments for the wife which would be mortgaged or sold off etc). This would take many more years to stop completely.
One important way to thwart this social evil, is to instill the evils of dowry system in the minds of the male child from an young age, so that neither will he ask for dowry for his marriage nor for the marriage of his son too.