In the fashion industry, this term refers to the phenomena of how a trend starts in an upscale market and then filters down to the masses. The psychology of differentiation and imitation is at the core of why members of the lower classes want to have what the upper classes have, especially in terms of clothing if they cannot have the lifestyle. The average lifecycle of a trend, from haute couture to mass merchandise, before the advent of television and the Internet, could take from one to two years. Now, as designers' runway shows air for all to see virtually immediately, styles are not only quick-changing but also being copied—and, in some cases, the knock-offs make it to the stores faster than the originals.
Historical Dictionary of the Fashion Industry. Francesca Sterlacci and Joanne Arbuckle.