I was asked about this, and I didn't know the answer. After looking around for a while I have found out that its an old pagan tradition, the bride wore a veil to keep evil spirits at bay that may try and take the purity of the Bride away. I have also found out that it used to be either red or yellow.
I have also seen that the veil is used so that the groom cannot see the bride before they're married, or to imply that the Groom thinks she's beautiful skin deep.
Modern veils have two parts to them, the top part is put over the brides head until after the ceremony.
We have a great range of wedding veils on our site, they come in many sizes and designs. http://www.tiptopweddingshop.co.uk/catalog/Bridal_Veils-408-1.html