Contemporary art is such a weathervane of fashion and money, it's easy to forget that, not so very long ago, its status was marginal rather than central.

Everyone wants a part of it now, but, for much of the last quarter of the 20th century, contemporary art was seen as something suspicious that needed to be handled with care. There were waymarks along the way to a shift in perception: the opening of the Guggenheim Bilbao in 1997 was one, the opening of Tate Modern in 2000 another. There is a third, though, that shows just how quickly contemporary art overran the established bastions of artistic taste: the first Frieze Art Fair in Regent's Park, London, in 2003.

The fair - a tented village at the south end of the park - was the idea of Matthew Slotover and Amanda Sharp, founders of the contemporary-art magazine Frieze. They had watched with interest international events such as Art Basel, the Armory Show in New York and Art Cologne that brought together the world's most significant galleries with collectors, and decided that London, with its burgeoning interest in modern art, needed something similar. Their inaugural fair hit the ground running, attracting 124 galleries and nearly 28,000 visitors, with sales amounting to £20m. By any objective measure this was a great success, but it showed up another, quite unexpected, side too: the public were fascinated, even though the vast majority had no intention of buying anything. The fair, by default, was seen as an entertainment (art-world types make for good people-watching) as well as a marketplace. Everyone was happy.

In subsequent years, Frieze has grown steadily: last year, 164 galleries from 27 countries participated, bringing in 55,000 visitors (its peak year was 2013 with 70,000), 80 per cent of whom were spectators. The organisers no longer release sales figures, arguing that many deals are struck away from Frieze once the initial contacts have been made there. It is safe to say, however, that the 2003 figure of £20m is now a drop in the ocean. Such is the fair's clout that Sotheby's, Phillips and Christie's schedule their contemporary-art sales for Frieze week, hoping to capitalise on the feeding frenzy of collectors attracted to the British capital by the fair.

Nonetheless, it would be a foolish entrepreneur who sat back and viewed his or her achievements with complacent satisfaction, so, in 2012, Frieze inaugurated two new incarnations: Frieze New York, a transatlantic version of the London fair, held in Randall's Island Park in May; and Frieze Masters, which shows works from antiquity to modern art and which, this year, coincides with Frieze itself. Other initiatives include a sculpture park around the tented hub, various guest-curated displays, and a Frieze Academy hosting a year-round programme of courses and talks.

What this means in practice is that, if you're in desperate need of a late-period Egyptian mummy mask from the 6th century BC, you'll be able to get one at Frieze. If, however, your need is for a sculpture of a rib cage made from plastic carrier bags, you'll be able to get that too. And everything in between.