When a potential home buyer can't get out right away to tour a listing, savvy real estate agents hold an open house on the potential buyer's computer screen.

Virtual tours aren't just a cool gimmick real estate agents use to show off their technological prowess.

Consumers demand them.

Seventy-eight percent of those who shop for homes on the Internet say the most important feature when searching online is photos -- followed closely by detailed property descriptions and virtual tours, according to the 2003 National Association of Realtors Profile of Home Buyers and Sellers.

What's more, those who demand virtual tours are more likely to be smarter, wealthier consumers in their prime home-buying years, compared to those who don't take tours. On a typical day, 2 million people are using the Internet to go on a virtual tour, according to the Pew Internet & American Life Project.

Those tours are not always virtual home tours. They also take viewers to far off places on Earth and beyond, say, to Mars, and include vacation destinations, colleges, art exhibits, hotels, and notable homes like the White House and Taj Mahal.

Virtual home tours, however, are among some of the most common tours taken.

Pew's nationwide phone survey to examine the impact of the Internet interviewed 914 adults, 534 of whom are Internet users.

The survey said those who take tours were more often single, white, women, aged 28 to 49, earning $50,000 a year or more, graduate degree holders and broadband access subscribers.

Home buyers like virtual home tours because they provide them with an immediate and efficient way to view and eliminate the homes they don't like and choose the homes they want to go see in person. For sellers it can mean less foot traffic, but just as many, if not more eyeballs on their home for sale.

It's a particularly common tool in the high-end market, where the best are professionally produced in living color, often with voice-overs as if the real estate agent is along for the tour. The best are also easy to navigate, allowing you to smoothly tour the listing room by room, as if you were walking through the home and looking up and down, left and right.

Virtual home touring isn't without its critics.

There are both security and personal privacy issues. Some say criminals could use tours to case the home and if the home becomes a crime scene the virtual tour could be seized (online) and used as forensic evidence to search for clues in the case.

Technology has improved immensely and costs have plummeted since the first jerky images rotated with fits and starts on a computer screen, but it still takes a clean, speedy broadband connection or a download to a computer with a fast video processor to fully enjoy the tour without unwanted stop-action.

Overall, the Pew study said, 45 percent -- 54 million -- of American adults who use the Internet have taken virtual tours, but more -- 60 percent -- of those who have broadband connections at home and 62 percent of those who have broadband connections at work have taken virtual tours of some type.

Virtual home tour making also takes skilled professionals to output high-quality, life-like videos. A virtual home tour produced unprofessionally can harm a listing more than help it.

Occasionally, the best virtual tour may not be of the home itself, but, say, of its unobstructed view of the ocean, hillsides or meadow. Putting a home's unique feature in its best light with a virtual tour and leaving the rest to good old still photography remains an option.

For example, it's nearly impossible to overcome "bloating" rooms when the confines of a small space forces the virtual tour maker to snap on the wide angle lens to capture the flow of the room.

Real Hollywood magic on the silver screen or an in-person visit remains necessary to see a home as it really exists.