Why are wedding dresses white?

A son asked his mother the following question:

‘Mom, why are wedding dresses white?’

The mother looks at her son and replies:  ‘Son, this shows your friends and relatives that your bride is pure.’

The son thanks his Mom and goes off to double-check this with his father…  ‘Dad why are wedding dresses white?’

The father looks at his son in surprise and says:  ‘Son, all household appliances come in white.’