Twice a year, the fashion industry gathers for a week to see the new collections. Fall is shown in February; spring, in September. But in late May and June, brands across the fashion spectrum present collections for a season known as “resort” (or, more quaintly, “cruise”).

Once a blip on the radar between fall and spring, resort collections used to be a few extra pieces to amuse the ladies heading to sunny locales during winter months. Today, however, resort means serious business.

Last week, many labels, including BCBG Max Azria and Collette Dinnigan presented their wares in showrooms around town. Others chose to stage full runway shows. First out of the box was Christian Dior on May 14, then Chanel in Los Angeles on May 21. Oscar de la Renta presented his resort pieces last week, and Carolina Herrera’s collection will be presented today.

Does everyone suddenly need an entire winter-in-the-sun wardrobe? Hardly. The title “Resort” is largely an anachronism. It’s really prespring, and its purpose is simple supply and demand. Consumers want new merchandise more frequently, and retailers want to give it to them. If shopping is the dominant activity in a consumer culture, then there need to be new things to shop for; the expectation that there will be something new must be met.

It’s an almost insatiable appetite that has driven fashion to a speed so absurd that trends virtually evaporate before they hit the streets. Fast-fashion brands, such as H&M and Zara, push the cycle almost to its limits. And depending on how you see it, the increased importance of resort collections is either a response to or a cause of the quickened speed and hyperactive demand.

Resort collections are delivered to stores in between the traditional two major seasons. Fall clothes are shipped to retailers in June and might stay on the floor until November. Spring clothes roll around in February and are sold through May, with discounts right about now, in mid-June through early July.

Resort offers a bridge between spring and fall; it is shipped in October and is sold until March. For emerging brands, the in-between season gives the customer a chance to see the line develop and jump in. The menswear label Rag & Bone, for instance, launched its women’s line in 2005; next week it will present its first full-fledged resort collection. According to owner and partner David Neville, the need to grab the customer’s attention again and again is paramount.

“If you made a delivery in August and that’s all until February, it’s not that inspiring,” Mr. Neville said. “I don’t know how often a Barneys shopper goes in the store, but it’s probably about once a week.”

And as the selling season moves on, the Resort pieces can be mixed in with spring. “What we’re finding is that it’s something that the retailers can carry over into spring,” Mr. Neville said. “It helps the other product that might be on the floor, too.”

With these collections, designers test the waters for trends and play with different weights of fabrics. If something worked well for fall, it can be produced in a lighter fabric for spring. It also has an inherent extended selling season, the creative director of BCBG Max Azria and Max Azria, Lubov Azria, said. “Resort can be reordered. It’s the one that makes the most money.”

There was an excellent example of that versatility in the 2008 resort collection of Max Azria, which is the creative girl’s answer to its sister line, BCBG. A red cotton dress with flounces at the top and one shoulder exposed could be worn in late spring through summer, and even in the warmest days of fall. If a retailer sold out in February, there could be a second shipment in May and the dress would still be attractive.

For a high-end label such as Douglas Hannant, resort plays a broad role, its president, Frederick Anderson, said. “Resort has become really important. It’s transition. Not just travel anymore. You really only have three months to sell spring.”

That’s because Douglas Hannant is selling chiffon gowns with stone embellishment and bubble dresses made of sequined tulle. Those pieces are not going to fly off the shelves come midsummer. “By the time you get to spring, it’s so hot that it’s time for summer casual. Who’s going to pay $2,000 for shorts?” Mr. Anderson said.

At the high end, there is still a connection to the original idea of the resort collection. The Douglas Hannant client migrates from Boston, New York, or Chicago to a second home in Florida or Texas, where she has a social life and wardrobe needs similar to her primary residence. “She has the need. She goes to a warmer client,” Mr. Neville said.

For those who aren’t going to a warmer client, the added merchandise floods the racks and makes for more shopping. The speed of fashion does, however, result in oddities. Try finding a decent bikini in July. But it’s also a system that results in more of everything. And by all evidence, that’s what consumers want.

pcatton@nysun.com