Why do men pay Dowry ( Bride Price) before marriage??

Image Source: Pixels.com:Free Stock:Misha Earle

In some cultures of the world ; it is mandatory that the groom pay a price before marrying the Bride !

Is this the practice in your community??

Why is it necessary for the Groom to pay such a price ??

Is it more cultural than necessary??

Why not the Bride paying for the Groom as it is in other cultures ???

Which do you prefer??