For Amazon.com, its evolution may come down to a patent leather, open-toe pump.

The online retailer Wednesday opened a new shoe and handbag store, one that raises the stakes for competitors and has the potential to change the way it hawks wares in other categories.

Endless.com -- the first stand-alone U.S. retail site Amazon has started from scratch -- includes the unique (and expensive) feature of free overnight shipping on all its 250 brands and 15,000 styles for men, women and children.

The site also matches offers from other online shoe sites, including free return shipping up to 365 days after the purchase and a 110 percent price guarantee.

While many of its competitors have begun to offer free standard shipping, none offers free overnight shipping due to high costs.

Zappos.com, among the largest shoe and handbag sites, offers free standard shipping but charges $25 for one-day service. At Nordstrom.com, renowned for its extensive shoe selection, standard shipping is $5 while two-day runs $12.50.

"We thought about what would be the best shoe experience in the world," said Steven Goldsmith, Amazon's vice president of soft goods and Endless.com.

Amazon has invested significant time and money on technology and shipping promotions in recent years.

After finding success in its first promotion -- one that offered to foot the shipping bill for orders worth $25 or more -- the company introduced Amazon Prime as a way to test one of the final barriers to online shopping.

For $79 a year, the membership program offers "all you can eat" two-day shipping on all orders, and overnight shipping for an additional $3.99 per item.

While the program is designed to encourage subscribers to buy more frequently from its site, its convenience comes at a cost.

For the nine months that ended Sept. 30, Amazon brought in $375 million in shipping revenue but spent $567 million to fulfill orders.

Goldsmith declined to discuss how the new site would manage costs but said it has use of Amazon's extensive distribution network. "We're able to leverage the advantage we have," he said.

Endless.com also incorporates new and extensive search technology that enables customers to search by price, style, brand, size and color, both together or separately.

Among its other features: If a customer places a cursor over the product photo, it offers a close-up of any part of the product.

Once a customer clicks on a product, search results appear at the top of the page in a scrolling film-strip, so customers don't have to click the "back" button to view other styles.

In 2005, Zappos doubled sales over the prior year to $370 million. Meanwhile, it forecast $600 million in shoe and handbag sales last year. Gap -- among the largest retailers with brands such as Gap, Old Navy, Banana Republic and Forth & Towne -- recently launched its own shoe store, Piperlime.com.

Endless.com marks a departure for Amazon, which has assembled a vast selection of items across 36 categories mostly through third-party sellers.

While Amazon offers everything from furniture to makeup, media products continue to account for the majority of sales.

For the nine months that ended Sept. 30, sales of books, music, videos and DVDs accounted for 67.9 percent of the company's $6.73 billion in revenue.

Opening a separate store might be a way to distinguish the store for online shoppers who still view Amazon as a place to buy books.

Goldsmith declined to say whether Amazon would use the same approach in other categories.

Amazon customers are accustomed to a certain shopping experience, he said. Launching a separate site enabled it to offer features most relevant to shopping for shoes and handbags.

"It's an alternative," Goldsmith said. "It's an additional way to shop."

Amazon's shares closed at $38.70 Wednesday, down 76 cents.