The brick-and-mortar retail business (still in operation) was spun off in the early 1990s.

In most cases, brick-and-mortar businesses resent the competition.

This revolution, after all, was about making brick-and-mortar businesses obsolete.

In 1992, Brice moved out of a brick-and-mortar business to establish a home-based business, providing travel planning and executive assistance.

Pop-ups frequently function as trial balloons for brick-and-mortar businesses, testing concepts with less financial risk.

These sites range from shadowy operations without known addresses to well-established brick-and-mortar businesses like the Pill Box, a five-store chain based in San Antonio.

And many thousands of them now face the task of bringing brick-and-mortar businesses into the future.

The chief executives of dot-coms brag about how they never hire anyone over 35, while brick-and-mortar businesses dump older workers when they merge or the economy dips.

"We've been really good at attracting brick-and-mortar businesses," Mr. Yap said.

Such businesses may actually be hurting their established brick-and-mortar businesses by creating a reputation of poor customer service that might not exist for walk-in customers.