Where flagging began is a tricky investigation in history, with a handful of theories leading the way to the truth. From hanky flagging to carabiners, to jewellery, keys and nail designs the code of flagging is popularly believed to have been 'launched; in the 1970s by Alan Selby. Coming from an overorder of bandanas, hanky flagging is one of the pedestals of gay flagging with pocket and colour creating a plethora of codes both relating to sexuality and sexual availability (often being used more popularly by the kink community in modern history). From then onwards, the hanky code has become only the beginning of a dictionary of new codes helping millions of people flag every day.
In the 1980s, an iconic lesbian magazine On Our Backs adapted the hanky code for the lesbian lifestyle with a sale of handkerchiefs alongside the edition. Since then, the hanky code in its original form has greater evolved into new forms amongst the women loving women community; taking form in nail designs. Being coined the "femme-icure" this universal flag is inseparable from the sapphic community, featuring long nails on every finger except the middle and pointer. Some examples of the colour-coded femme-icure can look like a sparkling (often silver) ring finger meaning femme-for-femme, however, more often the colours reflect that of the hanky code.
While the hanky code and "femme-icure" are two titans of the flagging world, they are not the only universally understood forms of communication in fashion. To indicate sexual preferences women loving women have often worn keys or carabiners attached to their trousers. Often, people who have recently discovered their sapphic identity and are searching for ways to express it will learn that the carabiner is a universal symbol for to women loving women. Flagging extends beyond the kink, gay, lesbian and bisexual community however, also applying to the asexual community. Traditionally, the asexual community flags through jewellery, most popular being the "ace ring". This is a plain black ring, usually worn on either the right hand, specifically the middle finger.
The hanky code or flagging process once went out of fashion, however, in recent history; likely because of the influx of social media, it has regained popularity. It's also easier and safer to express queer identity than the 1970's or 80's, however, don't assume that everyone takes part in flagging. Many use these symbols and codes as a reminder they aren't alone, and the outward pride they receive from that is a bonus. Regardless of relationships with the process, flagging is back and this time it seems here to stay - it can only further evolve from here.