You often hear designers and fashion journalists talking about something called the 'Fashion Cycle.' It's a sort of unspoken, universal rule of fashion that dictates how trends live and die. What is interesting is that in recent times, the fashion cycle has seriously shortened and although the '20 year rules' still holds true to an extent (that what was popular 20 years beforehand 'comes back around' in varying incarnations), the truth is that as the garment lifecycle diminishes, so does the trend lifespan.
Where are trends born?
Trends used to be 'born' from the brains of designers. Creative, attentive to culture and social context, in the 20th-century designers, tended to create fashion from their own influences and experiences. During times of social upheaval or difficulty (recession, war), trends arose from 'what people had' rather than what they wanted. Being resourceful led to what became fashionable. For example, when 'blackouts' were imposed in wartime Britain, a trend for glow-in-the-dark accessories emerged. The original 'street style' trends were present in the form of subcultures but would only achieve widespread adoption through celebrity figureheads in the music or film industry with the means to popularise styles through large concerts or films (think Punk and The Sex Pistols, or the Hippy indie films of the 60s and 70s).
In the 21st century, things have changed. In the early noughties, there was still a fairly rigid 'fashion hierarchy' in place. The top glossy magazines (think Vogue, Harper's Bazaar, W) and editors curated the catwalk for their readers and offered summaries of the main trends for the seasons. You would get your fashion fix by scouring a limited number of websites or by buying a magazine and having a thumb through the editorials.
In the past five years, however, the democratisation of fashion has given the power to the people. Trends no longer 'trickle down' from catwalk to magazine, to personal wardrobe, but now also 'trickle up.'
How do trends begin online?
Large audiences are no longer needed for the dissemination of trends, just the virality and uniqueness to appeal to online news outlets such as Buzzfeed. A multiplier effect takes place when trends begin on social media, and when journalists and cultural commentators can collate several styles of the same trend from multiple different sources: they have a story. Influencers with followers in the tens of thousands begin to adopt the trend, giving it the mainstream appeal that seems more authentic and directly applicable to everyday life to people than the catwalks ever did, and by this time, the Zaras of the world are listening up: for the people have spoken (or, you know, "liked & shared").
The benefit of trends trickling up is that the demand is already there and readily made. The brands and designers are not having to thrust their goods on people hoping that they will want them but can take an almost data-driven approach to what they put out there, when, and how. This phenomenon has happened most recently with ruffled sleeves in cotton shirts, gingham check and flared trousers.
How do trends “die”?
The way that trends die has more or less stayed the same. Once the market reaches a saturation point, the trend is in every shop on the high street, in varying iterations and at increasingly lower price, the trend has now 'died.' It may still be popular and widely worn, but the 'tastemakers' at the top of the traditional fashion hierarchy and the 'influencers' who build their living on spotting the next 'big thing' must move on, to stay modern, creative and desirable.