Jon Coile, chairman of MRIS, the Rockville, Md.-based multiple-listing service, writes commentary on the Washington-area housing market.

In the early 1990s, I conducted a survey with top-producing real estate agents from across the country.

How many of you have been holding open houses?” I asked. Virtually everyone said yes, which wasn’t a surprise. Open houses have long been a staple of the real estate industry, even though their effectiveness was always subject to debate.

How many of you have actually sold a home at an open house to someone who walked in off the street?” I asked. Only about 1 percent replied that they had.

This year, that survey result is no longer valid. Thanks to the advent of online listings, the role of the open house is changing dramatically for both buyers and sellers: Open houses are now selling homes.

What’s changed? Well, 25 years ago, information about a property wasn’t as readily available as it is today. People would pull over and jump out of their cars when they saw an open house sign if a house had curb appeal. They’d have no idea whether it was in their price range as they walked in the door.

The popularity of online home search sites over the past few years is positively affecting the effectiveness of open houses. With homes listed online, buyers can learn everything about a house before they even set foot in it. When they pull up to the curb, they already know whether they can afford a home. They have likely already seen photos of all its features.

Even the very nature of open houses has changed. They are no longer limited to the old-school time slot of weekends from 1 to 4 p.m. Seller’s agents are holding open houses seven days a week. The key is to plan the open house to cater to the audience that would be best suited to live in the home and highlight the best attribute of the home or location.

For example, you might consider having a midweek happy hour with small bites from the hottest new restaurant if you are trying to attract young urban buyers. If the home’s neighborhood is known for the best pizzeria in town, have a weekday evening pizza party to show off the great location. Is your home’s back yard perfect for families and entertaining? Why not show it off by simply serving lemonade on the deck to encourage potential buyers to linger a little longer outside.

In June, more than 100 million unique visitors looked at houses on some of the major real estate Web sites, according to ComScore. For those who are ready to move from browsing for fun to actually wanting to get inside, an open house is a great way for them to experience what it would be like to live in a prospective home.