Some have written about why brides wear white - and yes it is nothing to do with purity and whether one is still a virgin when walking down the aisle.
And yes, it is partly to do with wealth. In the days before washing machines and easily washable fabrics, it was only the wealthy who would wear white as they were not the ones doing all the hard dirty work including the washing.
But the other reason was that brides would wear their new best dress for their wedding and the wealthy would wear the dress which they wore when being presented to the king or queen - the debutants! The dress would have a train usually attached at the shoulders which was known as a 'court train'.
And that is why many, many years later, brides still wear white and the dress will often have a train!
And why bridesmaids...? Get ready all you Christians....
the bridesmaids wear similar dresses to the bride to confuse the evil spirits so that they do not know which is the bride!