According to wedding tradition, the bride wears something “old” to remind the couple of the happiness of the courting period.
The bride wears something “new” to represent the hopeful success of the couple’s new life together, something “borrowed” to symbolize the support of friends, and something “blue” because it’s the color of fidelity.
If a bride wears a single girlfriend’s garter, it will improve that girl’s prospects of marriage.
That’s where the custom of the bride wearing “something old, something new, something borrowed, and something blue” to their weddings came from.