"Something old" is the first line of a traditional rhyme that details what a bride should wear at her wedding for good luck:
and a [silver] sixpence in her shoe.
The old item provides protection for the baby to come. The new item offers optimism for the future. The item borrowed from another happily married couple provides good luck. The colour blue is a sign of purity and fidelity. The sixpence — a British silver coin — is a symbol of prosperity or acts as a ward against evil done by frustrated suitors.
An 1898 compilation of English folklore recounted that:
In this country an old couplet directs that the bride shall wear:—"Something old, something new, something borrowed, something blue." "The something blue" takes, I am given to understand, usually the form of a garter, an article of dress which plays an important part in some wedding rites, as, for instance, in the old custom of plucking off the garter of the bride. "The something old" and "something blue" are devices to baffle the Evil Eye. The usual effect on the bride of the Evil Eye is to render her barren, and this is obviated by wearing "something borrowed", which should properly be the undergarment of some woman who has been blessed with children: the clothes communicate fertility to the bride.
The earliest recorded version of the first two lines is in 1871 in the short story, "Marriage Superstitions, and the Miseries of a Bride Elect" in St James' Magazine, when the female narrator states, "On the wedding day I must 'wear something new, something borrowed, something blue.'"
The first recorded version of the rhyme as we now know it (the so-called Lancashire version) was in a 1876 newspaper, which reported a wedding where the bride "wore, according to ancient custom, something old and something new, something borrowed and blue."
Another compilation of the era frames this poem as "a Lancashire version", as contrast against a Leicestershire recitation that "a bride on her wedding day should wear—'Something new, Something blue, Something borrowed'...", and so omits the "something old". The authors note that this counters other regional folklore warning against the wearing of blue on the wedding day, but relates the use of the colour to phrases like "true blue" which make positive associations with the colour.
The final line "and a sixpence in her shoe" is a later Victorian addition; the coin should be worn in the left shoe.
In 1894, the saying was recorded in Ireland, in the Annual Report and Proceedings of the Belfast Naturalists' Field Club, where it was attributed to County Monaghan folklore.
The wearing of the five items detailed in the rhyme is still popular in the UK and US.
In 2011, at the wedding of Prince William and Catherine Middleton, the bride had: